Patent Application
20240353637
This application claims the benefit of Indian application No. 202311028463 titled “TIGHT BUFFERED OPTICAL FIBER CABLE” filed by the applicant on Apr. 19, 2023, which is incorporated herein by reference in its entirety.
Embodiments of the present invention relate to the field of telecommunication fiber, a last mile optical fiber drop cable and more particularly, relate to a tight buffered optical fiber cable.
Optical fibers are widely used in optical cables. Single tight buffer based optical fiber cable face fiber retraction or tight buffer retraction issues during maximum load conditions. This retraction of fibers leads to breakage of spliced and/or connectorized fiber and loss of connectivity. In traditional cable constructions, free space is required to provide around the fibre module for optimum optical performances. This free space around the module in the cable core fails to provide enough static friction with the surrounding layer allowing free movement of the fibre module. Due to this, coupling of tight buffer modules with surrounding layers is not optimum and leads to fiber retraction during extreme environmental conditions in operations.
Optical fiber cables are utilized in a wide variety of applications. In many instances, the cables include tight buffered optical fibers. A tight buffered optical fiber typically includes an optical waveguide fiber, one or more protective coatings (e.g., a primary coating, a secondary coating, etc.) surrounding an outer surface of the fiber, and a polymeric buffer layer formed to surround the optical fiber and its protective coating(s). The buffer layer is formed in intimate contact with the protective coating(s). Many conventional materials utilized to form buffer layers may be subject to expansion and contraction as a result of environmental temperature and/or humidity variations. Buffer layer expansion and/or shrinkage (e.g., cold temperature shrinkage, etc.) can cause undesirable tensile and compressive forces to be transferred to the optical fibers, thereby resulting in degradation of the optical fiber performance.
Prior art KR20220051570A reference discloses an optical fiber cable with a central optical unit and having a water blocking tape (WBT) and aramid yarns. However, the WBT is placed between aramid yarns and sheath.
Prior art reference US2022373752A1 discloses a tight buffer cable having a WBT and aramid yarns. However, the WBT is placed between aramid yarns and sheath.
Prior art reference US2010150505A1 discloses an optical fiber cable (OFC) with a tight buffered fiber and one or more aramid yarns positioned for coupling with sheath.
Prior art reference EP2409190B1 discloses an OFC with a central optical unit and placement of aramid yarns with specific angular span between sheath and tight buffer to prevent adhesion.
The conventional optical fiber cable solutions disclosed in references such as KR20220051570A, US2022373752A1, US2010150505A1, and EP2409190B1 exhibit inherent deficiencies, specifically in the placement of water-blocking tape and tensile yarn, as well as the absence of an optimized dimensional configuration and necessary coupling between constituent components. These deficiencies collectively result in fiber retraction and undermine the overall performance of the cable system. The innovation described in this patent application addresses these shortcomings, presenting a technical advancement that significantly enhances the reliability and effectiveness of optical fiber cable systems.
Further, the current solutions encounter difficulties associated with the available free space surrounding the fiber module, resulting in less than optimal coupling with adjacent layers and the occurrence of fiber retraction under operational conditions.
Additionally, the optical communication industry has identified a persistent need for an optical fiber cable characterized by optimal dimensions and components, aiming to mitigate the drawbacks inherent in traditional cables. Notably, these drawbacks include challenges associated with fiber retraction and susceptibility to connectivity loss, particularly under extreme environmental conditions ability of optical fiber cables in diverse and challenging operational scenarios. Further, the existing solutions are marked by suboptimal placement of water-blocking tape, inadequacies in tensile yarn positioning, and a deficiency in achieving an optimal cable dimension and requisite coupling between components.
Accordingly, to overcome the disadvantages of the prior art, there is an urgent need for a technical solution that overcomes the above-stated limitations in the prior arts by providing an optical fiber cable with an optimal dimension. Thus, the present disclosure directly addresses these industry concerns, representing a notable technical advancement in the field by presenting a solution that significantly improves the performance. The proposed invention provides a tight buffered optical fiber cable.
Embodiments of the present invention relates an optical fiber cable comprises an optical fiber, a buffer layer that surrounds the optical fiber to define a tight buffered optical fiber, a deformable layer wrapped around the tight buffered optical fiber, one or more tensile yarns disposed above the deformable layer a sheath that surrounds the deformable layer and the one or more tensile yarns (108a-108n). The deformable layer has two longitudinal overlap ends that defines an overlap portion. Moreover, centre of the overlap portion of the deformable layer and a centre of a tensile yarn of the one or more tensile yarns is separated by a predefined angular distance with respect to the centre of the cable at one cross section along a length of the optical fiber cable. Further, the predefined angular distance is greater than or equal to 60 Degrees (60°).
In accordance with an embodiment of the present invention, the one or more tensile yarns comprising at least 1 yarn and at most 6 yarns.
In accordance with an embodiment of the present invention, the deformable layer is a water blocking tape (WBT).
In accordance with an embodiment of the present invention, width of the overlap portion is less than 4 millimetres (mm).
In accordance with an embodiment of the present invention, the angular distance between the centres of two or more tensile yarns of the one or more tensile yarns is greater than or equal to 30 degrees (30°) with respect to centre of the optical fiber cable (100).
In accordance with an embodiment of the present invention, the tight buffered optical fiber has an extra tight buffer length that is in a range of 0.04% to 0.2%. The tight buffered optical fiber retracts less than 5 mm/10 m when the optical fiber cable operates at a tensile load of greater than 400 Newton (N).
In accordance with an embodiment of the present invention, the centre of the overlap portion of the deformable layer and the centre of the tensile yarn of the one or more tensile yarns are separated by ≥90° angular distance with respect to centre of the optical fiber cable at atleast one cross section of the optical fiber cable (100).
In accordance with an embodiment of the present invention, the diameter of the optical fiber cable is less than 6 mm. The optical fiber cable has a breaking load that is in a range between 1350 Newton (N) and 2500 N. Further, the optical fiber undergoes a strain of less than 0.34% at an aerial load up to 150 N.
In accordance with an embodiment of the present invention, the stripping force of the tight buffered optical fiber is in a range between 1 N and 12 N for a sample of 20 mm tight buffered optical fiber.
In accordance with an embodiment of the present invention, the predefined angular distance is measured in one of, a clockwise direction and an anti-clockwise direction.
The foregoing objectives of the present invention are attained by providing a tight buffered optical fiber cable.
So that the manner in which the above-recited features of the present invention is understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
The invention herein will be better understood from the following description with reference to the drawings, in which:
The optical fiber cable is illustrated in the accompanying drawings, which like reference letters indicate corresponding parts in the various figures. It should be noted that the accompanying figure is intended to present illustrations of exemplary embodiments of the present invention. This figure is not intended to limit the scope of the present invention. It should also be noted that the accompanying figure is not necessarily drawn to scale.
The principles of the present invention and their advantages are best understood by referring to
The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and equivalents thereof. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. References within the specification to “one embodiment,” “an embodiment,” “embodiments,” or “one or more embodiments” are intended to indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention.
Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another and do not denote any order, ranking, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.
The conditional language used herein, such as, among others, “can,” “may,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps.
Disjunctive language such as the phrase “at least one of X, Y, Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.
Term “optical fiber” as used herein refers to a light guide that provides high-speed data transmission. The optical fiber includes one or more glass core regions and a glass cladding region. The light moving through the glass core regions of the optical fiber relies upon the principle of total internal reflection, where the glass core regions have a higher refractive index (n1) than the refractive index (n2) of the glass cladding region of the optical fiber.
Term “optical fiber cable” as used herein refers to a cable that encloses one or more optical fibers.
Term “tight buffered optical fiber” as used herein refers to a thermoplastic layer that may surround an optical fiber and in contact with a single optical fiber such that an inner diameter of the thermoplastic layer is substantially equal to an outer diameter of the optical fiber.
Term “deformable layer” as used herein refers to a layer having a shape that may be deformed using a small force. The layer can be wrapped over the tight buffered optical fiber.
Term “extra tight buffer length” as used herein refers to an additional length of tight buffer component with respect to length of a sheath of the optical fiber cable. In other words, the extra tight buffer length is the delta of length of the tight buffer as compared to the length of cable sheath.
Term “fiber retraction” as used herein refers to retraction of tight buffer or fiber in the cable is <5 mm/10 m when the cable is operating at a tensile load of >400 N. The unwanted retraction of optical fibers in cable leads to break of fibers and hence connectivity loss.
Term “stripping force” as used herein refers to an amount of force required to separate the optical fiber from the buffer layer (e.g., a thermoplastic buffer layer) without physically damaging the optical fiber or layers of the optical fiber.
The tight buffered optical fibers provides a novel configuration featuring a deformable layer, one or more tensile yarns, and precise angular distances between them effectively mitigating the issue of fiber retraction.
In particular, the optical fiber cable 100 has an optical fiber 102, a buffer layer 104, a deformable layer 106, one or more tensile yarns 108a-108n (hereinafter collectively referred to and designated as “the tensile yarns 108”), and a sheath 110. Moreover, the optical fiber 102 may be anyone of but not limited to, a single mode optical fiber, a multi-mode optical fiber, a single core optical fiber, and a multi-core optical fiber. Further, the optical fiber 102 may undergo a strain of less than 0.34% at an aerial load of up to 150 N.
The buffer layer 104 surrounds the optical fiber 102 and may define a tight buffered optical fiber 112. In particular, the tight buffered optical fiber 112 has a stripping force that may be in a range between 1 N and 12 N. Moreover, the tight buffered optical fiber 112 is easily strippable up to 30 millimeters (mm). In alternative embodiments, the tight buffered optical fiber 112 is easily strippable up to 20 millimeters (mm). Further, the buffer layer 104 may tightly or semi-tightly surround the optical fiber 102 to define the tight buffered optical fiber 112.
In different aspects of the present invention, the material of the buffer layer 104 may be anyone of but not limited to, polyethylene, low-smoke zero-halogen (LSZH), polyvinyl chloride (PVC), thermoplastic polyurethane (TPU), and the like.
In accordance with an embodiment of the present invention, the deformable layer 106 may be wrapped around the tight buffered optical fiber 112. In particular, the deformable layer 106 may have two longitudinal overlap ends 114a and 114b (hereinafter collectively referred to and designated as “the overlap ends 114”) that may define an overlap portion 116. Moreover, the deformable layer 106 may be but not limited to a water-blocking tape, a mica tape, a fire-retardant water blocking tape, a heat barrier tape, a polyester tape, and the like. Aspects of the present invention are intended to include and/or otherwise cover any type of deformable layer, without deviating from the scope of the present invention.
Further, the deformable layer 106 may be deformed with a force that may be less than 0.5 Newton. Alternatively, the deformable layer 106 may be deformed with a force that may be less than 1 N.
In some aspects, there may be free space present in-between the tight buffered optical fiber 112 and the deformable layer 106.
In accordance with an embodiment of the present invention, the overlap portion 116 may have a width that may be less than 4 mm. In particular, the overlap portion 116 having the width less than 4 mm may facilitate easier implementation in a small sized optical fiber cable. Moreover, the overlap portion 116 having the width less than 4 mm may eliminate the requirement of additional material for the deformable layer 106.
The tensile yarns 108 may be disposed above the deformable layer 106. Particularly, the centre 118 of the overlap portion 116 of the deformable layer 106 and a centre 120 of a tensile yarn of the tensile yarns 108 are separated by a predefined angular distance with respect to the centre of the cable 100 at least one cross section along a length of the optical fiber cable 100. The predefined angular distance may be greater than or equal to 60 Degrees (60°). Further, the predefined angular distance may be measured in any of, a clockwise direction and in an anti-clockwise direction.
Each tensile yarn of the tensile yarn 108 may be anyone of but not limited to, an aramid yarn, a glass roving yarn, and a poly-ethylene yarn.
In accordance with an embodiment of the sheath 110 may surround the deformable layer 106 and the tensile yarns 108. In particular, the material of the sheath 110 may be any but not limited to, polyethylene, low-smoke zero-halogen (LSZH), polyvinyl chloride (PVC), thermoplastic polyurethane (TPU), and the like.
In some aspects of the present invention, the tensile yarns 108 may have at least 1 yarn and at most 6 yarns.
In some aspects of the present invention, the deformable layer 106 may be a water blocking tape (WBT).
In some aspects of the present invention, the width of overlap portion 116 may be less than 4 millimetres (mm).
The angular distance between two or more tensile yarns of the tensile yarns 108 may be greater than or equal to 30 degrees (30°) with respect to the centre of the cable (100). In particular, the angular distance between two or more tensile yarns of the tensile yarns 108 greater than 30° enables uniform coupling of a tight buffer with an inner surface of the sheath 110. Moreover, the angular distance between two or more tensile yarns of the tensile yarns 108 greater than 30° may not allow two or more tensile yarns of the tensile yarns 108 to overlap with each other. The angular distance may be measured in any, a clockwise direction and an anti-clockwise direction.
In some aspects of the present invention, the tight buffered optical fiber 112 may have an extra tight buffer length in range of 0.04% to 0.2%. The tight buffered optical fiber 112 having the extra tight buffer length below than 0.04% may not be sufficient for bending and handling operations and may cause stresses to the tight buffered optical fiber 112. This may lead to physical damage to the tight buffered optical fiber 112. The tight buffered optical fiber 112 having the extra tight buffer length above than 0.2% may cause stress accumulation inside the core, which may generate excess radial pressure on the tight buffered optical fiber 112 which leads to degradation in optical property.
In accordance with an embodiment of the present invention the tight buffered optical fiber 112 may retract i.e., fiber retraction may be less than 5 mm/10 m when the optical fiber cable 100 operates at a tensile load of greater than 400.
In accordance with an embodiment of the present invention the optical fiber cable 100 may have an outer diameter that may be less than 6 millimeters (mm). Thus, making it light weight and reduces cost for installation of the optical fiber cable 100.
In accordance with an embodiment of the present invention, the centre 118 of the overlap portion 116 of the deformable layer 106 and the centre 120 of the tensile yarn of the tensile yarns 108 are separated by ≥90° angular distance with respect to centre of the cable (100) at minimum least one cross section of the optical fiber cable 100.
In accordance with an embodiment of the present invention, the optical fiber cable 100 has a plurality of embedded strength members 122a-122c (hereinafter collectively referred to and designated as “the strength members 122”). The strength members 122 may be arranged in the sheath 110 and provide the required tensile strength and stiffness to the cable 100. Each strength member of the strength members 122 are made up of a material, including but not limited to, reinforced aramid yarn, reinforced glass yarns, and steel.
In one aspect of the present invention, the centre 118 of the overlap portion 116 of the deformable layer 106 and the centre 120a of the tensile yarn 108a of the tensile yarns 108 are separated by at least 60° angular distance with respect to centre of the cable 300 at least one cross section of the optical fiber cable 300.
In alternative aspect of the present invention, the centre 120a of the tensile yarn 108a of the tensile yarns 108 and centre 120b of the tensile yarn 108b of the tensile yarns 108 are separated by at least 30° angular distance with respect to centre of the cable 300 at least one cross section of the optical fiber cable 300. Further, the centre 120b of the tensile yarn 108b of the tensile yarns 108 and centre 120c of the tensile yarn 108c of the tensile yarns 108 are separated by at least 30° angular distance with respect to centre of the cable 300 at least one cross section of the optical fiber cable 300.
In one or more aspect of the present invention, the optical fiber cable (100) characterizes an optical fiber (102), a buffer layer (104) that surrounds the optical fiber (102) to define a tight buffered optical fiber (112), a deformable layer (106) wrapped around the tight buffered optical fiber (112), where the deformable layer (106) has two longitudinal overlap ends (114a, 114b) that defines an overlap portion (116), one or more tensile yarns (108a-108n) disposed above the deformable layer (106) and a sheath (110) that surrounds the deformable layer (106) and the one or more tensile yarns (108a-108n). The centre (118) of the overlap portion (116) of the deformable layer (106) and centre (120) of a tensile yarn of the one or more tensile yarns (108a-108n) is separated by a predefined angular distance with respect to the centre of the cable (100) at minimum one cross section along a length of the optical fiber cable (100). Moreover, the angular distance between the centres of two or more tensile yarns of the one or more tensile yarns (108a-108n) is greater than or equal to 30 degrees (30°) with respect to centre of the optical fiber cable (100). The width of the overlap portion (116) is less than 4 millimetres (mm).
In one or more aspect of the present disclosure, the centre (118) of the overlap portion (116) of the deformable layer (106) and the centre (120) of the tensile yarn of the one or more tensile yarns (108a-108n) is separated by ≥90° angular distance with respect to centre of the optical fiber cable (100) at minimum one cross section of the optical fiber cable (100).
In one or more aspect of the present disclosure, the optical fiber (102) undergoes a strain of less than 0.34% at an aerial load up to 150 N. Further, the stripping force of the tight buffered optical fiber (112) is in a range between 1 N and 12 N for a sample of 20 mm tight buffered optical fiber.
In accordance with an embodiment of the present invention, the essential components of the invention includes a deformable layer, one or more tensile yarns positioned at specific angular orientations, and a protective sheath. The components collectively serve to prevent fiber retraction and significantly improve cable performance, particularly in the face of extreme operating conditions. Further, the collaboration between the deformable layer and the specified tensile yarns functions synergistically to prevent fiber retraction, ensuring an optimal and consistent coupling with surrounding layers. Further, the integration of components embodies an approach, offering enhanced reliability and performance in addressing the challenges associated with fiber retraction in optical fiber cables.
In accordance with an embodiment of the present invention, the precise angular positioning of the tensile yarns plays a pivotal role in achieving uniform coupling between the tight buffer unit and the sheath, thereby presenting a robust and highly effective solution to the identified problem.
The present invention pertains to mitigating the challenge of fiber retraction and associated connectivity loss observed in optical fiber cables, specifically under maximum load conditions.
Advantageously, the optical fiber cable 100 minimize the fiber retraction in the tight buffered cable and facilitate to uniformly couple the tight buffer with an inner surface of the sheath 110. The tensile yarns 108 may be strategically positioned outside the deformable layer 106 ensures a uniform coupling of the tight buffer with the sheath 110 at a plurality of locations and minimizes the fiber retraction during or after installation of the optical fiber cable 100 thereby making the optical fiber cable 100 easy to install. The unique placement of the tensile yarns 108 above the deformable layer 106 inside the optical fiber cable 100 may provide minimized fibre module retraction in operating conditions while having safe cable break technology. The unique placement of the tensile yarns 108 may keep strain produced at installation load of upto 150 N, less than 0.34%.
In addition to resolving fiber retraction challenges, the disclosed invention provides several other advantages, including achieving an optimal cable dimension, optimizing breaking load, cost-effectiveness, and a positive impact on overall cable performance. These collective benefits contribute to a more robust and efficient optical fiber cable system, surpassing the limitations of existing solutions.
In practical applications, the disclosed invention effectively prevents fiber retraction and improves cable performance in real-world operating conditions. This adaptability makes it well-suited for critical applications where optimal dimensions and connectivity are paramount, such as aerial installations or deployments under tension. In a broader context, the invention encompasses diverse optical fiber cable configurations incorporating deformable layers, tensile yarns, and specific angular distances. This inclusive approach offers a versatile solution to industry-wide challenges concerning fiber retraction and connectivity loss.
A person of ordinary skill in the art may be aware that, in combination with the examples described in the embodiments disclosed in this specification, units and algorithm steps may be implemented by electronic hardware, computer software, or a combination thereof.
The foregoing descriptions of specific embodiments of the present technology have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present technology to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present technology and its practical application, to thereby enable others skilled in the art to best utilize the present technology and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present technology.
Disjunctive language such as the phrase “at least one of X, Y, Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.
In a case that no conflict occurs, the embodiments in the present invention and the features in the embodiments may be mutually combined. The foregoing descriptions are merely specific implementations of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311028463 | Apr 2023 | IN | national |
