WO1996020820A1 - Procede de fabrication de fibres optiques - Google Patents

Procede de fabrication de fibres optiques Download PDF

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Publication number
WO1996020820A1
WO1996020820A1 PCT/US1995/000199 US9500199W WO9620820A1 WO 1996020820 A1 WO1996020820 A1 WO 1996020820A1 US 9500199 W US9500199 W US 9500199W WO 9620820 A1 WO9620820 A1 WO 9620820A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibers
rollers
polished
extrusion
optical fibers
Prior art date
Application number
PCT/US1995/000199
Other languages
English (en)
Inventor
Jack V. Miller
Original Assignee
Miller Jack V
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US08/063,770 priority Critical patent/US5393470A/en
Priority claimed from US08/063,770 external-priority patent/US5393470A/en
Application filed by Miller Jack V filed Critical Miller Jack V
Priority to PCT/US1995/000199 priority patent/WO1996020820A1/fr
Publication of WO1996020820A1 publication Critical patent/WO1996020820A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00663—Production of light guides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/05—Filamentary, e.g. strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/12—Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/304—Extrusion nozzles or dies specially adapted for bringing together components, e.g. melts within the die
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/345—Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00—Optical elements, e.g. lenses, prisms
    • B29L2011/0075—Light guides, optical cables

Definitions

  • This invention applies to the field of optical fiber manufacturing, and in particular to manufacturing thermoplastic optical fibers having a low refractive index cladding over a thermoplastic core of a higher index of refraction.
  • Such fibers as large as 3mm in diameter are finding use in display and sign illumination, as they are capable of transmitting high light levels.
  • the ability of these relatively large diameter fibers to transmit enough light to produce useful levels of visible illumination without any infrared oR ultraviolet energy makes them ideal for display lighting in such applications as museums and retail stores.
  • Presently-known plastic optical fibers are manufactured by one of two different and relatively expensive processes.
  • the very small- diameter holes in the dies through which the fibers are drawn must be drilled with either diamonds or lasers, and it is difficult to produce smooth, highly-polished holes.
  • any slight flaw or imperfection in the drawing die aperture is replicated in the drawn fiber and may cause a surface imperfection that functions as a light leak out of the core, whereby the internal reflection becomes less than total.
  • This method for drawing optical fibers is a slow and precise process, and the resulting cost of clad acrylic plastic fibers of 2mm to 3mm diameter needed for display illumination is presently in excess of $60 per pound of finished fiber material.
  • a second presently-used process for manufacturing plastic optical fibers produces what is know as "solid-core" fibers, in which a core of very soft and flexible polymer is extruded into a sheath of a fluorocarbon plastic which in part traps an air film about the core to provide the low index of refraction cladding.
  • Solid core fiber extrusion has all the manufacturing errors of clad acrylic fibers for the core, but additionally has a similar set of manufacturing errors for the pre-extruded sheath, requiring highly-polished small diameter surfaces for both the core and the sheath dies.
  • solid core fibers are normally less transmissive than clad acrylic fibers of the same diameter and length.
  • solid core process produces light guides of limited length, as it is not a continuous process.
  • manufacturing solid core fibers is an even more expensive process than acrylic fiber drawing.
  • the cost of producing fibers of 3mm diameter for display lighting is typically $250 per pound of 3mm diameter core material.
  • Light control sheets of this type are typically made by a machine in which a flat extruded thermoplastic sheet, often up to four feet wide, is continuously extruded from an extrusion press. While the extruded sheet is still plastic, it passes between a pair of highly-polished embossing rollers having prismatic embossing patterns thereon. The rollers apply the embossed pyramidal prismatic surfaces to the soft, extruded sheet. The rollers emboss, polish, cool and rigidize the plastic sheet, forming a continuous prismatic sheet that is then sawn into rectangular panels for installation into fluorescent light fixtures. This is a high-speed process, in which the large-diameter rollers produce very accurate and highly- polished surfaces on the plastic.
  • Prismatic lighting panel sheets of acrylic plastics are thus very inexpensively manufactured by this process, and are normally sold at a cost of less than $2 per pound.
  • the primary purpose of the present invention is to provide a manufacturing method for optical fibers that is a high-speed, high- volume process with the quality and cost advantages of pyramidal prismatic lighting sheet manufacturing, is combined with new rolling and cladding techniques to produce clad acrylic optical fibers at a significantly lower cost than presently-known fiber optics manufacturing methods.
  • the present invention for a process for manufacturing optical fibers, including extruding a transparent thermoplastic plastic in the form of a substantially flat extrusion having plurality of transversely shaped and spaced optical fibers, which are mutually connected in parallel grooves across the width of the extrusion, the grooves extending in the longitudinal direction of extrusion.
  • This process of the present invention uses a modification of existing machinery used in the production of pyramidal prismatic lighting diffusers, in which the thermoplastic sheet is rolled between polished rollers having upstanding circumferential ribs matching the shape and spacing of the grooves in the thermoplastic sheet. The rollers separate, polish and cool the thermoplastic extrusion into the form of a plurality of elongated fibers.
  • a preferred embodiment includes a first extruding die extruding said thermoplastic sheet having an index of refraction and a second extrusion die applying a coating of plastic having an index of refraction lower than the index of refraction of the transparent sheet.
  • the ribs form various channel shapes that may produce optical fibers in both circular and non-circular cross- sectional shapes which may be either symmetrical or non- symmetrical.
  • Figure 1 is a perspective view of the first embodiment of the process for manufacturing optical fibers according to the invention
  • Figure 2 is a transverse cross-sectional view of Figure 1 , taken along section line 2-2;
  • Figures 2a through 2c are alternate embodiments of Figure 2;
  • Figure 3 is a transverse cross-sectional view of Figure 1 , taken along section line 3-3;
  • Figures 3a through 3c are alternate embodiments of Figure 3;
  • Figure 4 is a longitudinal cross-sectional view of Figure 1 , taken along section line 4-4;
  • Figure 5 is a schematic flow diagram of the process of Figure 1 ; and Figure 6 is a schematic flow diagram of a simplified alternate embodiment of the process of Figure 5.
  • a process 1 for manufacturing optical fibers according to the present invention having a first extrusion die means including an extruder 2 injecting a transparent core polymer 3, such as acrylic or styrenic plastic, through an extrusion die 4 which is so configured to extrude a generally planar sheet 5 having a first surface 5a and second surface 5b including a plurality of transversely shaped and spaced parallel grooves 6 extending in the longitudinal direction D of the extrusion and forming a planar array of connected fibers having geometrically- shaped cross-sections.
  • a transparent core polymer 3 such as acrylic or styrenic plastic
  • Polished roller means 7 includes a first polished roller 8 and a second polished roller 9 rolling and imparting a polished surface to extrusion 5, at least one of rollers 8 or 9 having upstanding circumferential ribs 8a or 9a matching the shape and spacing of the grooves 6 in the extrusion, each rib of said first roller 8 contacting the second roller 9, thereby forming a geometrically-shaped channel 8b or 9b, imparting a polished surface to the fibers and parting the connected fibers into a plurality of separate elongated fibers 10 having polished and geometrically-shaped cross-sections.
  • the extrusion die means includes a second extruder 22 injecting a cladding polymer 13, having a lower index of refraction than core polymer 3, through a plurality of extrusion dies 14, so configured to form clad fibers 15.
  • Cladding polymer 13 may form a coating of thermosetting plastic which is cured by electromagnetic radiation from a curing accelerator 18 which may apply any of various electromagnetic radiation wavelengths, including ultraviolet or infrared energy to accelerate curing of polymer 13. It is not necessary to roller- polish the exterior of cladding polymer 13, as the optical interface is inside the cladding, against the fiber core 10.
  • a second roller means 19 may be included to cool and rigidize the clad fibers 15.
  • extrusion 5 having a generally planar configuration having a first surface 5a and second surface 5b including a plurality of transversely shaped and spaced parallel grooves 6 in the extrusion, forming a planar array of connected fibers having substantially round cross-sections.
  • FIG 3 an enlarged partial cross section of a preferred embodiment of extrusion 5 of Figure 2 is shown formed by first polished roller 8 having upstanding ribs 8a and second polished roller 9 having upstanding ribs 9a in contact with ribs 8a of roller 8, so as to separate the planar array of connected fibers of extrusion 5 of Figure 2 into separate fibers 10 having substantially round cross-sections.
  • FIG 2a an enlarged partial cross section of a second preferred embodiment of extrusion 35 is shown having a planar first surface 35a and second surface 35b including a plurality of transversely shaped and spaced parallel grooves 36 in the extrusion, forming a planar array of connected fibers having substantially hexagonal cross-sections.
  • FIG 3a an enlarged partial cross section of the second preferred embodiment of extrusion 35 of Figure 2a is shown having a planar first surface 35a and second surface 35b including a plurality of transversely shaped and spaced parallel grooves 36 in the extrusion, formed by first polished roller 38 having upstanding ribs 38a and second polished roller 39 having upstanding ribs 39a in contact with ribs 38a of roller 38, so as to separate the planar array of connected fibers of extrusion 35 of Figure 2a into separate fibers 30 having substantially hexagonal cross-sections.
  • FIG. 2b an enlarged partial cross section of a second preferred embodiment of extrusion 45 is shown having a planar first surface 45a and second surface 45b including a plurality of transversely shaped and spaced parallel grooves 46 in the extrusion, forming a planar array of connected fibers 40 having substantially trapezoidal cross-sections.
  • FIG 3b an enlarged partial cross section of the second preferred embodiment of extrusion 45 is shown having a planar first surface 45a and second surface 45b including a plurality of transversely shaped and spaced parallel grooves 46 in the extrusion, formed by first polished roller 48 having upstanding ribs 48a and second polished roller 49 having upstanding ribs 49a in contact with ribs 48a of roller 48, so as to separate the planar array of connected fibers of extrusion 45 of Figure 2b into separate fibers 40 having substantially trapezoidal cross- sections.
  • FIG. 2c an enlarged partial cross section of a third preferred embodiment of extrusion 55 is shown having a planar first surface 55a and second surface 55b including a plurality of transversely shaped and spaced parallel grooves 56 in the extrusion, forming a planar array of connected fibers having substantially triangular cross-sections.
  • FIG 3c an enlarged partial cross section of a third preferred embodiment of extrusion 55 of Figure 2c is shown having a planar first surface 55a and second surface 55b including a plurality of transversely shaped and spaced parallel grooves 56 in the extrusion, formed by first polished roller 58 having upstanding ribs 58a and second polished roller 59 having upstanding ribs 59a in contact with ribs 58a of roller 58, so as to separate the planar array of connected fibers of extrusion 55 of Figure 2c into separate fibers 50 having substantially triangular cross-sections.
  • Extruder 12 includes a plurality of entrance dies 22 which loosely guide fibers 10 into cladding polymer 13, except along parting lines 10a, which are smoothed and polished by dies the entrance 22. Extruder 12 also includes a plurality of exit dies 24 which apply a thin coating 25 cladding polymer 13 to core fibers 10, producing clad fiber 15.
  • FIG 5 a schematic flow diagram of the process of Figure 1 is shown in which the manufacturing process includes the following operations: Extrude Grooved Sheet 80; Cut Grooved Sheet Into Fibers 71 ; Form Fiber Into Final Shape 72; Polish Fibers 73; Cool Fibers 74; Apply Cladding 75; and Cure Cladding 76.
  • FIG 6 a schematic flow diagram of a simplified alternate embodiment of the process of Figure 5 is shown in which the manufacturing process includes the following operations: Extrude Fibers 80; Form Fibers Into Final Shape 81 ; Polish Fibers 82; Cool Fibers 83; and Apply Cladding 84.
  • the foregoing description of a process for manufacturing optical fibers is adapted from the most efficient and low cost processes for manufacturing prismatic light control lens sheets for the fluorescent fixture industry in a new combination with the techniques for producing optical fibers.
  • the difficulty in producing small- diameter individual fiber drawing dies that are flaw-free is overcome, by transferring the finishing process to large rollers that may be highly polished, thus producing a superior finish on the fibers in a high-speed process.
  • simultaneous extrusion and rolling in a 48-inch-wide extrusion press as many as 350 fibers of 3mm diameter may be made, thereby reducing the manufacturing cost of optical fibers to near that of producing embossed prismatic sheets.
  • the process of the present invention is capable of producing fibers of sharp-cornered geometric shapes, such as hexagons, trapezoids and triangles, which form bundles substantially without interstices, providing for more efficient acceptance of illumination.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Ophthalmology & Optometry (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

Procédé (1) de fabrication de fibres optiques qui consiste à extruder une feuille (5) thermoplastique transparente dotée d'une pluralité de rainures (6) parallèles transversales espacées qui s'étendent dans le sens longitudinal d'extrusion. Ladite feuille thermoplastique (5) est laminée entre des rouleaux (7, 8) polis dotés de nervures (8a, 8b) circonférentielles saillantes coïncidant avec la forme et l'espacement des rainures (6) dans la feuille thermoplastique (5). Lesdits rouleaux (7, 8) séparent la feuille thermoplastique extrudée en une pluralité de fibres allongées (10) et polissent et refroidissent les fibres séparées. Dans un mode de réalisation préféré, une première filière d'extrusion (4) extrude la feuille thermoplastique (5) ayant un indice de réfraction et une seconde filière d'extrusion (22) applique un revêtement de plastique (25) coextrudé ayant un indice de réfraction plus faible que l'indice de réfraction de la feuille transparente (5). Les nervures des rouleaux (8, 9) polis forment diverses formes (8b, 9b) de canal qui peuvent produire des fibres optiques à section transversale circulaire ou non circulaire.
PCT/US1995/000199 1993-05-20 1995-01-04 Procede de fabrication de fibres optiques WO1996020820A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US08/063,770 US5393470A (en) 1993-05-20 1993-05-20 Process for manufacturing optical fibers
PCT/US1995/000199 WO1996020820A1 (fr) 1993-05-20 1995-01-04 Procede de fabrication de fibres optiques

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/063,770 US5393470A (en) 1993-05-20 1993-05-20 Process for manufacturing optical fibers
PCT/US1995/000199 WO1996020820A1 (fr) 1993-05-20 1995-01-04 Procede de fabrication de fibres optiques

Publications (1)

Publication Number Publication Date
WO1996020820A1 true WO1996020820A1 (fr) 1996-07-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/000199 WO1996020820A1 (fr) 1993-05-20 1995-01-04 Procede de fabrication de fibres optiques

Country Status (1)

Country Link
WO (1) WO1996020820A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2728950A (en) * 1954-05-06 1956-01-03 Dow Chemical Co Process for producing fibers from films of polymeric materials
US3470285A (en) * 1967-08-04 1969-09-30 Hercules Inc Making synthetic filaments from fibrillated film
US3736217A (en) * 1969-09-29 1973-05-29 American Optical Corp Light-conducting fiber material
US4083914A (en) * 1967-04-01 1978-04-11 Barmag Barmer Maschinenfabrik Aktiengesellschaft Methods for production of filaments from foils

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2728950A (en) * 1954-05-06 1956-01-03 Dow Chemical Co Process for producing fibers from films of polymeric materials
US4083914A (en) * 1967-04-01 1978-04-11 Barmag Barmer Maschinenfabrik Aktiengesellschaft Methods for production of filaments from foils
US3470285A (en) * 1967-08-04 1969-09-30 Hercules Inc Making synthetic filaments from fibrillated film
US3736217A (en) * 1969-09-29 1973-05-29 American Optical Corp Light-conducting fiber material

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