HK1124396B - Fiber optic cables and methods for forming the same - Google Patents

Description

Optical fiber cable and method of forming the same

RELATED APPLICATIONS

【0001】 The disclosures of U.S. provisional patent application No. 60/688,492, filed on 8.6.2005 and U.S. provisional patent application No. 60/688,493, filed on 8.6.2005, the disclosures of which are hereby incorporated by reference in their entireties, are claimed herein.

Technical Field

【0002】 The present invention relates to transmission cables, and more particularly to fiber optic transmission cables and methods of forming the same.

Background

【0003】 Array fiber optic connectors have traditionally been applied to ribbon fiber cables and cables, tight buffered cables, and loose tube cables. Each of these cables has inherent disadvantages in terms of cable cost, cable performance, and connectorization methods.

【0004】 Ribbon cables can be more expensive than other cable designs and can be subject to preferential bending. The optical performance of ribbon cables may also be degraded due to the cable construction. Furthermore, a fork or a forked hose may be required to separate and lead the multiple bands to the multiple connectors.

【0005】 Tight buffered cables are typically larger cables that reduce the packing density of the optical fibers and negatively impact handling considerations for such cable assemblies. Additional work may involve connectivity, as each individual tight buffer typically must be stripped and then protected with a furcation tube. Ribbonizing of the loose fibers may also be required prior to application of the arrayed fiber optic connector.

【0006】 Loose tube cables have advantages in optical performance, cable size and cable cost. Traditionally, however, the optical fiber must be protected with a furcation tube. Likewise, ribbonizing of loose-packed optical fibers may also be required prior to application of the arrayed optical fiber connector.

Disclosure of Invention

【0007】 According to an embodiment of the present invention, a loose tube fiber optic cable includes at least one cable unit. Each cable unit includes: a plurality of loose-buffered optical fibers; a strength yarn at least partially surrounding the unbuffered optical fiber; and a jacket surrounding the strength yarn and the unbuffered optical fiber.

【0008】 According to some embodiments, the unbuffered optical fibers each have a diameter ranging from about 235 to 265 μm.

【0009】 According to some embodiments, each cable unit is configured to have its said unbuffered optical fiber float in its said jacket.

【0010】 According to some embodiments, the jacket of each cable unit has an outer diameter ranging from about 2.75 to 3.25 mm.

【0011】 According to some embodiments, the cable further comprises: an outer strength yarn surrounding at least a portion of the at least one cable unit; and an outer jacket surrounding the outer strength yarn and the at least one cable unit.

【0012】 According to some embodiments, the at least one cable unit comprises a plurality of the cable units, the cable further comprising an outer jacket surrounding the jackets of the plurality of cable units.

【0013】 According to a further embodiment of the present invention, a connectorized cable assembly comprises: a loose-tube fiber optic cable including at least one cable unit; and an optical fiber connector mounted on the at least one cable unit. Each cable unit includes: a plurality of loose-buffered optical fibers; a strength yarn at least partially surrounding the unbuffered optical fiber; and a jacket surrounding the strength yarn and the unbuffered optical fiber.

【0014】 According to a method embodiment of the present invention, a method of forming a loose-tube fiber optic cable includes: forming at least one cable unit, the cable unit comprising: a plurality of loose-buffered optical fibers; a strength yarn at least partially surrounding the unbuffered optical fiber; and a polymer jacket surrounding the strength yarn and the unbuffered optical fiber.

【0015】 Those of ordinary skill in the art will recognize from a reading of the figures and the following detailed description of the preferred embodiments (such description is intended to be illustrative of the present invention only)

Further features, advantages and details of the invention.

Drawings

【0016】 FIG. 1 is a cut-away perspective view of a cable according to an embodiment of the present invention.

【0017】 Fig. 2 is a cross-sectional view of an unbuffered optical fiber forming a portion of the cable of fig. 1.

【0018】 Fig. 3A is a front perspective view of a connectorized cable assembly including the cable of fig. 1 according to an embodiment of the invention.

【0019】 Fig. 3B is an exploded front perspective view of the connectorized cable of fig. 3A.

【0020】 Fig. 3C is a cross-sectional view of the connectorized cable of fig. 3 taken along line 3C-3C of fig. 3A.

【0021】 FIG. 4 is a cut-away perspective view of a cable according to a further embodiment of the present invention.

【0022】 FIG. 5 is a cut-away perspective view of a cable according to a further embodiment of the present invention.

【0023】 FIG. 6 is a cut-away perspective view of a cable according to a further embodiment of the present invention.

Detailed Description

【0024】 Illustrative embodiments of the invention are shown in the drawings, and the invention will be described more fully hereinafter with reference to the accompanying drawings. The dimensions of regions or features in the figures may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

【0025】 It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements present. Like reference numerals refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

【0026】 Furthermore, spatially relative terms, such as "under," "below," "lower," "over," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can include both an orientation "above" and an orientation "below". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

【0027】 Well-known functions or constructions may not be described in detail for brevity and/or clarity.

【0028】 The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and/or "the" meaning of the indefinite articles "or" the "may be translated (e.g.," the "," said "and/or" not translated ") are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

【0029】 Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

【0030】 According to an embodiment of the present invention, a loose tube fiber optic cable is provided. The cable may provide the advantages of loose tube routing and/or reduce or eliminate certain cable assembly efforts and costs that are typically necessary when utilizing other fiber optic routing types and solutions.

【0031】 Referring to fig. 1, a cable 100 according to an embodiment of the present invention is shown. Cable 100 generally includes a plurality of unbuffered optical fibers 110, a plurality of strength yarns 120, and a protective jacket 130. According to some embodiments and as shown, the cable 100 is circular in cross-section, with the components of the foregoing combination being positioned substantially concentrically about and extending together along the length axis L-L. The cable 100 may be combined with the connector assembly 10 to form a connectorized cable 5, as shown in fig. 3A-3C. These components will be described in more detail below.

【0032】 As shown, cable 100 includes a bundle 111 of twelve (12) unbuffered optical fibers 110 a. According to some embodiments, the optical fibers 110 are loose with respect to each other such that they do not have a particular, fixed relative orientation.

【0033】 One example of an optical fiber 110 is shown in cross-section in FIG. 2. The optical fiber 110 includes a glass fiber 112, the glass fiber 112 including a glass core 112A and a surrounding glass cladding 112B. The glass fibers 112 may be constructed in any suitable manner. For example, each of the core 112A and the cladding 112B may include one or more concentric segments or layers, may be doped, and the like. The glass fibers 112 may be made of any suitable material using any suitable method.

【0034】 Referring again to FIG. 2, in the optical fiber 110, a coating 114 surrounds the cladding 112B. The coating 114 provides environmental protection to the glass fiber 112. As shown, the coating 114 is comprised of a single coating; however, multiple concentric layers may also be applied to form the overall layer 114. According to some embodiments, the coating 114 is made of a uv-cured acrylate. The coating 114 of the respective optical fibers 110 may have different colors for color coding purposes.

【0035】 According to some embodiments and as shown, the optical fiber 110 is an optical fiber that is configured to be commonly referred to as a "bare fiber" or an "unbuffered fiber". According to some embodiments, the total diameter D1 of the optical fiber 110 ranges from about 235 to 265 μm. According to some embodiments, the thickness T1 of coating 114 is not greater than about 70.5 μm. According to some embodiments, the overall diameter D1 is between about 235 and 265 μm, and the thickness T1 of the coating 114 is no greater than about 70.5 μm. According to some embodiments, the diameter D2 of the core 112A is between about 6 and 64 μm and the diameter D3 of the cladding 112B is between about 115 and 135 μm.

【0036】 As shown, cable 100 further includes a bundle 121 of strength yarns (strength yarns) 120, where strength yarns 120 at least partially surround fiber optic bundle 111. The strength yarns 120 may be made of any suitable material. According to some embodiments, the strength yarns 120 are aramid fibers. Other suitable materials may include fiberglass or polyester. According to some embodiments, the strength yarns 120 each have a denier ranging from about 250 to 3000. According to some embodiments, the strength yarn bundle 121 includes about 2 to 10 ends or strands of the strength yarns 120 (each end or strand of the strength yarns 120 may include hundreds of filaments).

【0037】 A jacket 130 surrounds yarn bundle 121 and fiber bundle 111, with yarn bundle 121 and fiber bundle 111 residing in a longitudinal channel 132 defined by jacket 130. The sheath 130 may be made of any suitable material, such as a polymeric material. According to some embodiments, the sheath 130 is made of a thermoplastic polymer. Suitable polymeric materials may include PVC (polyvinyl chloride), PVDF (polyvinylidene fluoride), or FRPE (flame retardant polyethylene). The jacket 130 may be molded or extruded over the optical fiber bundle 111 and the strength yarn bundle 121. According to some embodiments, the thickness T2 of the sheath 130 is between about 0.20 and 1.0 mm.

【0038】 According to some embodiments, the inner diameter D4 of the jacket channel 132 is greater than the combined cross-sectional diameter of the optical fiber bundle 111 and the strength yarn bundle 121, such that at least the optical fibers 110 are loose and thus able to float within the channel 132 (i.e., able to move freely relative to the jacket 130). According to some embodiments, both the optical fibers 110 and the strength yarns 120 are loose and both float within the channel 132 (i.e., are free to move relative to the jacket 130). Thus, at least a portion of the volume of the channel 132 is not filled with the optical fiber 110 or the strength yarn 120, thereby allowing the optical fiber 110 and the strength yarn 120 to move within the channel 132. According to some embodiments, at least 30% of the volume of the channel 132 is unfilled by the optical fiber bundle 111 and the strength yarn bundle 121 (i.e., the cross-sectional area of the channel 132 is at least 30% greater than the combined total cross-sectional area of the optical fiber bundle 111 and the strength yarn bundle 121). According to some embodiments, between about 50% and 60% of the volume of the channel 132 is unfilled by the bundles 111, 121 (i.e., the cross-sectional area of the channel 132 is between about 50% and 60% greater than the combined total cross-sectional area of the bundles 111, 121). The cable 100 may be referred to as a "loose tube cable".

【0039】 According to some embodiments, the cable 100 has an overall outer diameter D5 of about 1.5 to 4 mm. According to some embodiments, the outer diameter D5 is between about 2.75 and 3.25 mm. A cable 100 having an outer diameter D5 of between about 2.75 and 3.25mm is commonly referred to as a 3mm cable.

【0040】 Suitable apparatus and methods for forming cable 100 will be apparent to those skilled in the art. The optical fiber bundle 111 and the strength yarn bundle 121 may be twisted together and then the jacket 130 molded or extruded thereon. The optical fibers 110 may be helically stranded (e.g., using reverse shimmy or S-Z techniques). The cable 100 may then be packaged (e.g., wound on a roller) or cut into various lengths. The cable 100 is thus prefabricated as shown in the figures. The cable 100 may be packaged and used as a stand-alone cable or may be incorporated into a cable unit or subunit of a larger cable such as described below.

【0041】 The cable 100 may provide a number of advantages. The cable 100 may allow for direct connection to a connector, such as an array fiber optic connector (e.g., a multi-fiber push-on (MPO) fiber optic connector). The strength yarns 120 may provide strain relief at the connector. The loose tube configuration and circular shape may provide improved optical performance, cable size, cable cost, handling, and reliability characteristics. The cable may have a reduced diameter so that its space requirements better fit into cabinets, cable trays, ducts, etc. The cable may have a reduced weight, which may reduce the mounting force on the cable and may provide easier handling. The cable may provide improved robustness, thereby providing a safety margin with respect to standard requirements. Loose tube cables can reduce problems such as preferential bend radius, kink crush resistance, and the like. Because the optical fiber 110 is an unbuffered optical fiber, the connector is installed without first stripping the tight buffer from the optical fiber (e.g., in the field). The pre-manufactured cable 100 may enable the optical fibers 110 to be directly connected to a connector with strain relief without the use of furcation tubes, additional strength yarns, and the like. Thus, the overall assembly cost may be reduced by reducing the complexity of the connection process.

【0042】 Referring to fig. 3A-3C, cable 100 may be terminated with connector assembly 10 to form the connectorized cable assembly or cable 5 shown. The connector assembly 10 is exemplary and other suitable connectors may be used. The connector assembly 10 includes a front housing 20, a hole plug (ferule) 22, a hole plug sleeve 24, a pin clip 26, a spring 28, a rear housing 30, a crimp ring (crimp ring)32, and a strain relief boot 34. As shown in fig. 3C, the optical fiber 110 is secured in the plug by epoxy 36. As also shown in fig. 3C, the strength yarns 120 are secured directly to the connector assembly 10 by crimping the strength yarns 120 between the jacket 130 and the connector rear housing 30 using crimp rings 32. In this way, the strength yarns 120 provide strain relief. The connector assembly 10 is mounted directly on the cable 100 and the round jacket 130 without the use of a fork tube or the like. If desired, the relatively thin coating 114 may be stripped or washed off the ends of the respective glass fibers 112; the installer does not have to strip off the relatively thick tight-buffer coating (which may be present on 900 μm buffered optical fiber, for example). According to some embodiments, the connector assembly and/or method of installing the connector assembly includes the connector assembly and/or method disclosed in commonly assigned U.S. provisional patent application serial No. 60/688,492 (attorney docket No. 9457-48), filed on 8/6/2005, the disclosure of which is hereby incorporated by reference. According to some embodiments, the end segments 111A (fig. 3B) of the fiber bundles 111 within the housings 20, 30 are ribbonized such that the portions of the optical fibers 110 therein are arranged in a side-by-side single row configuration. Segment 111A may be temporarily or permanently held in this banded configuration by a strip of tape or adhesive 111B.

【0043】 According to some embodiments, the connector cable assembly 5 is a cable that includes a length of cable 100 and respective connector assemblies 10 mounted at both ends of the cable 100. The two connector assemblies 10 may be configured to be the same or different from each other. According to some embodiments, the strength yarns 120 are crimped or otherwise secured directly to the two connector assemblies. That is, the strength yarns 120 extend continuously from one connector assembly 10 to the other connector assembly and may provide strain relief at both connector assemblies.

【0044】 Referring to fig. 4, a cable 201 is shown according to a further embodiment of the present invention. The cable 201 includes a cable unit 200 constructed in the same manner as the cable 100, the cable unit 200 including optical fibers 210, strength yarns 220, and a jacket 230. The bundles 241 of outer strength yarns 240 surround the jacket 230 (which may be referred to as an "inner jacket") of the cable unit 200. The outer jacket 250 defines a passage 252 and surrounds the yarn bundle 241 and the cable unit 200. Tear strip 244 also extends through passage 252. According to some embodiments, the outer jacket 250 is a loose fit around the strength yarn bundles 241 such that the cable units 200 and the strength yarns 240 float in the jacket channel 252.

【0045】 The cable unit 200 of the cable 201 can be connectorized in the same manner as described above. The strength yarns 240 and the outer jacket 250 may provide additional tensile strength to the cable 201, thereby providing protection to the optical fibers 210.

【0046】 The strength yarns 240 may be constructed as described above for the strength yarns 120. The outer sheath 250 may be formed as described above for the sheath 130. According to some embodiments, the outer sheath 250 has a thickness of between about 0.40 and 1.0 mm.

【0047】 Referring to fig. 5, a cable 301 according to a further embodiment of the present invention is shown. The cable 301 includes two cable units 300. Each cable unit 300 is constructed in the same manner as cable 100 and includes optical fibers 210, strength yarns 220, and a jacket 330 (which may be referred to as an "inner jacket"). The outer jacket 360 defines a passage 362 and surrounds the cable unit 300. Tear strip 344 also extends through channel 362. The cable units 300 may extend in parallel as shown. Alternatively, the cable unit 300 may be helically stranded (e.g., using reverse shimmy or S-Z techniques). The sheath 360 may be constructed as described above for the sheath 130. According to some embodiments, the outer sheath 360 has a thickness of between about 0.30 to 1.0 mm. According to some embodiments, the outer jacket 360 is a loose fit around the cable unit 300 such that the cable unit 300 floats within the outer jacket 360. Talc powder or other lubricant may be placed in the outer sheath channel 362 to prevent binding or bonding between the sheaths 360 and 330.

【0048】 Cable 301 can be used in the manner described above. Cable 301 provides twenty-four (24) optical fibers. Each of the cable units 300 is separable from the cable 301 and connectorized with a respective connector.

【0049】 Referring to fig. 6, a cable 401 is shown according to a further embodiment of the present invention. Cable 401 includes twelve (12) cable units 400 to provide a total of 144 unbuffered optical fibers 410. Each cable unit 400 is constructed in the same manner as the cable unit 300. The outer jacket 460 defines a passage 462 and surrounds the cable unit 400. A tear strip 444 also extends through the passage 462. Alternatively, a Glass Reinforced Polymer (GRP) fiberglass rod 446 extends through the sheath passage 462. A bundling tape 448 is helically wound around the cable unit 400 to hold the cable unit 400 in place during manufacture. The cable unit 400 may be helically stranded (e.g., using reverse shimmy or S-Z techniques). The jacket 460 may be formed as described above for jacket 130. According to some embodiments, the outer jacket 460 has a thickness of between about 0.30 to 1.0 mm. According to some embodiments, the cable unit 400 is loosely fit in the jacket 460 such that the cable unit 400 floats in the passage 462. Talc powder or other lubricant may be provided in the passage 462 to prevent the outer jacket 460 from sticking or bonding with the respective jackets of the cable units 400.

【0050】 Cable 401 can be used in the same manner as described above for cable 301, except that cable 401 can be split to provide twelve connectorized sub-cables or cable subunits.

【0051】 Although each cable unit 100, 200, 300, 400 has been illustrated as having twelve optical fibers each, such cable units may include more or fewer optical fibers. Furthermore, according to some embodiments, cables corresponding to cables 301 or 401 may be made with more or fewer cable units 300, 400.

【0052】 According to some embodiments, the cables described herein comply with at least one of the following specifications: GR-409-CORE Issue 1 (issued 5 months 1994), general requisitions for premises Fiber optical Cable; ICEA S-83-596-; NFPA-262, Revision 2 (issued on 19.7.2002), Standard Method of Test for flametrack and paint of Wires and Cables for Use in Air-Handling Spaces; and UL-1666, 4^thEdition (issued on 12.7.2002), Test for Flame-Propagation and Smok-sensitivity Values for electric and Optical-fiber cards inserted vertical in Shafts. According to some embodiments, the cable complies with each of the aforementioned regulations.

【0053】 The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.

Claims (20)

1. A connectorized cable assembly comprising:

a) a loose-tube fiber optic cable including at least one cable unit, each cable unit including:

a plurality of loose-buffered optical fibers;

a strength yarn at least partially surrounding the unbuffered optical fiber; and

a jacket surrounding the strength yarns and the unbuffered optical fiber;

wherein the unbuffered optical fibers are loose with respect to all optical fibers surrounded by the jacket such that they have no particular, fixed relative orientation; and

b) a fiber optic connector mounted on the at least one cable unit, wherein the strength yarns are secured directly to the connector to provide strain relief at the connector.

2. The connectorized cable assembly of claim 1, wherein the unbuffered optical fibers each have a diameter ranging from 235 to 265 μ ι η.

3. The connectorized cable assembly of claim 1, wherein each of the unbuffered optical fibers includes a core, a cladding surrounding the core, and at least one coating surrounding the cladding.

4. The connectorized cable assembly of claim 3, wherein the at least one coating of each unbuffered optical fiber has a thickness of no greater than 70.5 μm.

5. The connectorized cable assembly of claim 3, wherein the at least one coating of each unbuffered optical fiber is made of an acrylate.

6. The connectorized cable assembly of claim 3, wherein the coating of at least some of the unbuffered optical fibers contacts the strength yarns of the respective cable units.

7. The connectorized cable assembly of claim 1, wherein each cable unit is configured with its the unbuffered optical fiber floating in its jacket.

8. The connectorized cable assembly of claim 1, wherein each cable unit is configured with its strength yarns floating in its jacket.

9. The connectorized cable assembly of claim 1, wherein each cable unit includes a plurality of the strength yarns at least partially surrounding the unbuffered optical fiber thereof and surrounded by the jacket thereof.

10. The connectorized cable assembly of claim 1, wherein the strength yarns of each cable unit are made from a material selected from the group consisting of aramid, fiberglass, and polyester.

11. The connectorized cable assembly of claim 1, wherein the jacket of each cable unit has an outer diameter ranging from 1.5 to 4 mm.

12. The connectorized cable assembly of claim 11, wherein the jacket of each cable unit has an outer diameter ranging from 2.75 to 3.25 mm.

13. The connectorized cable assembly of claim 1, comprising:

an outer strength yarn surrounding at least a portion of the at least one cable unit; and

an outer jacket surrounding the outer strength yarns and the at least one cable unit.

14. The connectorized cable assembly of claim 13, wherein outer strength yarns and the outer jacket surround only one and only one cable unit.

15. The connectorized cable assembly of claim 13, comprising a plurality of outer strength yarns surrounding the at least one cable unit, wherein the outer jacket surrounds the plurality of outer strength yarns.

16. The connectorized cable assembly of claim 1, wherein the at least one cable unit includes a plurality of the cable units, the cable further including an outer jacket surrounding the jackets of the plurality of cable units.

17. The connectorized cable assembly of claim 16, wherein the at least one cable unit includes at least three cable units surrounded by the outer jacket.

18. The connectorized cable assembly of claim 16, wherein the plurality of cable units are helically wound within the outer jacket.

19. The connectorized cable assembly of claim 1, wherein the cable includes a plurality of the at least one cable unit, each of the plurality of cable units including a respective fiber optic connector mounted thereon.

20. A method of forming a loose-tube fiber optic cable, comprising:

forming at least one cable unit, the cable unit comprising:

a plurality of loose-buffered optical fibers;

a strength yarn at least partially surrounding the unbuffered optical fiber; and

a polymer jacket surrounding the strength yarns and the unbuffered optical fiber;

wherein the unbuffered optical fibers are loose with respect to all optical fibers surrounded by the jacket such that they have no particular, fixed relative orientation; and

installing a fiber optic connector on the cable unit with the strength yarns secured directly to the connector to provide strain relief at the connector.