Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/02—Optical fibres with cladding with or without a coating
  • G02B6/02033—Core or cladding made from organic material, e.g. polymeric material

Definitions

• the invention is in the field of optical elements and is to be used in the design of fiber-shaped optical waveguides which are made of polymeric plastics and are provided with a multilayer protective covering.
• Optical waveguides are suitable on the one hand for transmitting large amounts of data and on the other hand for interference-free, i.e. Data transmission that cannot be influenced by electromagnetic fields.
• the inexpensive plastic light guides are suitable for data transmission over short distances of up to approx. 100 m, for example in the fields of mechanical engineering, automotive engineering and the office sector.
• the basic structure of these light guides which are also referred to as "polymer optical fibers", has an optical core, an optical jacket and a protective sheath.
• the core and sheath have a diameter of approximately 1 mm, the protective covering a wall thickness of approximately 0.2 to 1 mm.
• the choice of material for the core for example polymethyl methacrylate
• the sheath for example a fluoropolymer such as polyvinylidene fluoride or polytetrafluoroethylene
• the choice of material for the protective sheathing serves to improve the property profile of the polymeric optical fiber to adapt to the particular environment in which the optical fiber is used (magazine "Draht", 1995, Issue 4, pages 187 to 190; Conference Publication IMechE, 1981, C192 / 180, pages 227 to 229: "Multiplexed Wi ⁇ ng m the automobile: near term possibility ").
• the protective covering of a polymeric optical fiber is formed in a single layer, for which purpose, inter alia, the Use of the materials polyethylene, polyvinyl chloride and chlorinated polyethylene is known.
• This protective covering can contain soot to prevent the penetration of extraneous light into the polymeric optical fiber.
• polyamide, polyurethane or polyoxymethylene can also be used as the material for the single-layer protective covering. These materials can also be enriched with fire protection agents
• thermoplastic elastomers as the material for the protective covering of polymer optical fibers and to construct this covering in multiple layers.
• thermoplastic elastomers As the material for the protective covering of polymer optical fibers and to construct this covering in multiple layers (EP 0 395 823 B1).
• different plastics with the same or different values of the Young's module can also be used (EP 0 162 471 AI).
• a material for the protective sheathing that has a shape retention temperature of at least 120 °.
• the material for the protective covering for example a polycarbonate, being enriched with organic or inorganic fillers such as carbon black, talc, glass fibers, fibers made from an aromatic polyamide or carbon fibers.
• the protective covering can also be formed in two layers, the inner layer serving as a cushion for the outer layer.
• one or two additional coatings can be applied over the protective covering, for example from a polyethylene which can be crosslinked under the action of moisture.
• a polymeric optical fiber can be used in the engine compartment of a motor vehicle for data transmission or for sensory purposes (EP 0 183 853 B1).
• the invention has for its object to design the protective cover so that the property profile of the optical fiber can be easily adapted to different mechanical and chemical / requirements and to different usage properties.
• the protective sheath consists of at least three co-applied, firmly interconnected layers, of which the first, inner layer consists of a natural-colored thermoplastic, the second layer, the opaque layer and a third outer layer consists of a colored thermoplastic.
• the at least three-layer design of the protective sheath provided in accordance with the invention and the joint application of these layers result in a large variation. tion width with regard to the performance characteristics of the optical fiber.
• the inner, natural-colored layer ensures mechanical and optical decoupling of the optical core and the optical cladding from the other layers.
• the use of a natural-colored plastic closes the mechanical action of color particles or other filler particles on the optical cladding of the fiber and thus an influence the optical damping.
• This inner layer preferably consists of a thermoplastic elastomer, such as a polyurethane or a polyether block amide. These materials offer good protection against damage to the fiber due to dust-like soiling on the surface of the optical cladding during the opening of the protective cover.
• the substances mentioned also allow a defined adhesive fit of the protective covering on the optical jacket without increasing the lateral pressure. They also enable safe removal of the protective jacket with regard to the installation of plugs.
• the second layer arranged over the inner layer is opaque, which is usually achieved in a plastic layer by adding carbon black.
• D e ⁇ lichtun take lassige layer may also consist of a low-melting metal, and thus also form a diffusion barrier and / or be used for the transmission of low-power electric pulses.
• the low-melting metals used for this purpose are preferably alloys based on bismuth such as special solders or the Woods metal, the melting temperatures of which are in part below the extrusion temperature of heat-resistant plastics.
• connection of such a metal layer with adjacent plastic layers can be ensured by adhesion promoters that are applied as a thin intermediate layer at the same time as the other layers - for example through the multi-layer extrusion practiced in film production.
• An adhesion promoter in the form of a thinner intermediate layer can also be used for the firm connection of two plastic layers.
• the outer third layer of the protective cover generally offers the possibility of clearly identifying the optical fiber by introducing any dye
• a colored layer can be seen more clearly than e.g. printing applied to a black layer, which can also cause manufacturing problems.
• the third outer layer can also be enriched with further additives or fillers in order to ensure special mechanical or physical or chemical properties. If necessary, a special layer with these properties can be arranged as a fourth layer between the opaque layer and the third embossed layer.
• the property profile of the new optical fiber can also be determined by selecting different plastics for the different layers.
• plastics include in particular polyamide, polyurethane, polyester, polyolefms, polyvinyl chloride, polyacetals and fluoropolymers.
• the property profile of the protective sheath and thus the fiber can also be determined by a special shape of the second and third layers, for example by a surface corrugation of the second layer, which consists of a rigid material such as polyamide, and one with a smooth surface arranged third layer made of a soft material such as polyurethane.
• Such a configuration ensures high jerk forces after bending, for example after storing a fiber in the wound state.
• the performance characteristics of the new protective cover also depend on the thickness of the individual layers. These thicknesses should be approximately 50 to 200 ⁇ m for the inner and the opaque layer and approximately 20 to 800 ⁇ m for the third outer layer; preferably the wall thickness of each of the two inner layers is approximately H the wall thickness of the outer layer.
• Suitable layer combinations for the construction of the protective cover include: damping and light emission,
• thermal properties such as temperature resistance and flame resistance
• physiological harmlessness such as suitability for laying in drinking water
• FIGS. 1 to 4 Three exemplary embodiments of the new optical fiber are shown in FIGS. 1 to 4.
• 1 shows a polymeric optical fiber with a three-layer protective covering made of polyamide
• FIG. 2 shows a fiber with a four-layer protective covering made of different plastics
• Figure 3 is an optical fiber with a special mechanical structure of the protective cover
• Figure 4 shows an optical fiber with an opaque layer of metal.
• FIG. 1 shows a cross-sectional sector of a polymeric optical fiber 1 which initially comprises the optical core 11 made of, for example, polymethylacrylate and the optical cladding 12 made of, for example, polyvinylidene fluoride.
• a protective covering composed of three layers is applied to the jacket 12, each layer consisting of a polyamide and the three layers extruded together in a triple injection head and thereby connected to one another in their border areas and applied together to the optical jacket 12.
• the inner layer 13 consists of a non-embossed, that is, natural-colored polyamide, the second layer 14 of a polyamide enriched with carbon black and therefore opaque, and the outer layer 15 of a polyamide enriched with a dye.
• the inner layer 13 and the middle layer 14 serve essentially for the optical quality of the polymeric optical fiber, while the outer layer 15 of the protective sheath essentially determines the mechanical properties, the chemical properties and the product design.
• the two layers 13 and 14 have a wall thickness of approximately 100 ⁇ m, while the outer layer 15 has a wall thickness of approximately 400 ⁇ m.
• the polymeric optical fiber 2 according to FIG. 2 is constructed in the same way as the fiber according to FIG. 1 with regard to the optical core 11 and the optical cladding 12. enriched polyamide.
• Layer 23 is a further layer from a copolymer based on ethylene and Vmyl acetate, which is made flame-retardant by adding aluminum oxide hydrate.
• embossed layer 24 made of a fluoropolymer. - This structure of the polymer optical fiber takes into account in particular the optical properties as well as thermal properties such as flame resistance and temperature resistance.
• a three-layer protective covering is applied to the optical cladding 12 which surrounds the optical core 11 and which consists of the inner layer 21 made of a polyurethane or also of a polyether block amide, an opaque layer 41 made of a consists of soot-enriched polyamide and an outer layer 42 made of an embe-colored polyurethane.
• the outer boundary surface of the layer 41 is corrugated in the longitudinal direction of the optical fiber, i.e. the wall thickness is subject to regular fluctuations in the longitudinal direction.
• the thaler thus formed are filled in by the layer 42.
• the special design of layer 41 and the choice of material for layer 42 produce special mechanical properties, namely a high restoring force against bending with sufficient flexibility.
• a five-layer protective covering is applied to the optical core 11 and the optical jacket 12.
• This consists of the inner layer 21 made of an undyed polyurethane, a thin adhesive layer 31, an opaque layer 32 made of a low-melting metal, a further adhesive layer 33 and an outer layer 34 made of an embossed polyvinyl chloride.
• This structure of the protective cover takes account of environmental influences in particular, because the metal layer 32 provides protection against the permeation of moisture, gases and liquid media also represents and takes into account the property "electrical conductivity".

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
• Laminated Bodies (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (3)

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Citations (4)

• 1998
  • 1998-08-12 CN CN 98808682 patent/CN1269021A/zh active Pending
  • 1998-08-12 RU RU2000107818A patent/RU2000107818A/ru not_active Application Discontinuation
  • 1998-08-12 EP EP98948786A patent/EP1008000A1/de not_active Ceased
  • 1998-08-12 JP JP2000509008A patent/JP2001515223A/ja not_active Withdrawn
  • 1998-08-12 WO PCT/DE1998/002334 patent/WO1999012063A1/de not_active Application Discontinuation

Patent Citations (4)

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