DESC:FIELD OF INVENTION
[0001] The present invention, in general, relates to optical fibre ribbons. More particularly, the present invention relates to an intermittently bonded optical fibre ribbon with uniform matrix material density having flexibility and folding characteristics for proper bundling.

BACKGROUND OF THE INVENTION
[0002] In typical fibre optic cables, the optical fibre ribbons are a convenient solution when a high fibre density within a small space is required or there is a requirement of quick splicing using mass fusion splicing or any other splicing method. The optical fibre ribbons are coated optical fibres placed side by side. In an optical fibre cable, as the number of fibres increase, the identification of the optical fibre at the opposite ends of the cable becomes difficult. For optical fibre cable having less fibre count, the cable manufacturer uses colored optical fibres (16 colors, preferably 12 colors) for identification. Further, for the optical fibre cables with more than 12 fibres, for example, more than 100 fibres, the optical fibre ribbons are the preferred solution. In an optical fibre ribbon, the colored optical fibre (4 to 16 colored optical fibres) are arranged in parallel and coated with a matrix material throughout the longitudinal length of the optical fibres (also called flat ribbon).
[0003] Folding or collapsing of the flat ribbon in the width direction is not possible as the fibres are fully encapsulated in the matrix material throughout the length of the ribbon as well as in the width direction of the ribbon. Because of the high density of the matrix material, the bond breaks while folding in the width direction. Also, if the ribbons are arranged in the form of the stack (rectangular stack) in the buffer tube, it takes more space, hence increases the diameter of the buffer tube as well as the diameter of the optical fibre cable.
[0004] The patent document US10782495B2 discloses a method of making an optical-fibre ribbon, comprising (i) arranging a plurality of optical fibres into a longitudinal optical-fibre assembly, wherein the plurality of optical fibres are parallel and respectively adjacent to each other, and wherein each optical fibre includes, from its center to its periphery, a glass core, a glass cladding, a primary coating, a secondary coating, an ink layer, and a sacrificial, outer release layer formed of a first curable resin that is less than completely cured, the sacrificial, outer release layer contiguously surrounding the ink layer; (ii) applying a second curable resin to a surface of the optical-fibre assembly, wherein the second curable resin forms a plurality of successive elongated rectilinear beads configured to form bonds between adjacent optical fibres in the optical-fibre assembly; and (iii) passing the optical-fibre assembly with the surficial, elongated rectilinear beads through a curing station to cure the second curable resin and to further cure the first curable resin.
[0005] The patent document US8787718B2 discloses an optical fibre ribbon includes four single-core coated optical fibres arranged in parallel on the same plane, and coupling parts arranged at intervals in a length direction and a width direction, each coupling only adjacent to two of the single-core coated optical fibres, wherein an interval of the coupling parts coupling the same two single-core coated optical fibres is not less than 20 mm nor more than 90 mm and a length of each of the coupling parts is not less than 1 mm nor more than 10 mm.
[0006] The patent document US8548294B2 discloses a mono-coated optical fibre that has a bending loss characteristic in which an optical loss increase at a bending radius 13 mm is 0.2 dB/10 turn or less, an optical fibre ribbon that includes two-dimensionally disposed resin portions for bonding the adjacent 2-fibre mono-coated optical fibres in plural places, the resin portions being disposed apart from each other in the longitudinal direction of the optical fibre ribbon and an optical fibre cable that includes a cable core portion that stores twisting of plural units where the mono-coated optical fibres constituting the optical fibre ribbon are collected.
[0007] The patent document US9989723B2 discloses an optical fibre ribbon comprises a plurality of optical fibre strands that are arranged side-by-side in one direction and integrated. The optical fibre ribbon comprises a plurality of optical fibre strands that are bonded in parallel. In the optical fibre ribbon, the adjacent optical fibre strands are bonded using bonding sections in which the same are continuously bonded along the entire length thereof and a bonding section in which the same are intermittently bonded at prescribed intervals. In other words, either of the bonding sections is formed between the adjacent optical fibre strands.
[0008] The patent document JP4143651B2 discloses an optical fibre ribbon composed of three or more optical fibres arranged in parallel, a plurality of connecting portions that connect only two adjacent optical fibres, are two-dimensional in the longitudinal direction and the width direction of the optical fibre ribbon. The length of the connecting portion provided intermittently and applied to the same optical fibre is shorter than the length of the unconnected portion of the same optical fibre, and the width of the optical fibre ribbon between connecting portions adjacent to each other in a direction they are spaced apart in the longitudinal direction of the optical fibre ribbon, and the optical fibre ribbon, characterized in that they are staggered so as not to overlap in the width direction.
[0009] The patent application US20170219790A1 discloses a method for making a partially bonded optical fibre ribbon. The method includes providing a linear array of optical fibres and applying a bonding matrix material randomly to at least a portion of at least two adjacent optical fibres. The bonding matrix material is applied randomly to the adjacent optical fibres in such a way that the linear array of optical fibres forms a partially bonded optical fibre ribbon. The bonding matrix material applied randomly to the adjacent optical fibres is dense enough to allow the resulting partially bonded optical fibre ribbon to lay substantially flat. Also, the bonding matrix material applied randomly to the adjacent optical fibres is sparse enough to allow the resulting partially bonded optical fibre ribbon to be rolled into a substantially circular shape.
[0010] Now, the cable manufacturers are making an intermittently bonded ribbon (IBR) in which the bonds are provided at a specific distance to improve the folding of the optical fibre ribbon in width direction for proper bundling of ribbon in a cable without using buffer tubes, while maintaining the planarity of the optical fibre ribbon as the planarity of the optical fibre ribbon is a most important factor for splicing more than one fibre simultaneously. In current available intermittently bonded ribbons, the bonds along the length of the ribbons are in such a way that the number of bond in the width direction varies from 0 to 11 in the ribbon (considering 12F ribbon) along the length. When the density of the matrix material along the width, varies throughout the length of the optical fibre ribbon, it makes it difficult for proper bundling of ribbons in a uniform cylindrical form as the attenuation increases in a compact bundling. The available intermittently bonded ribbons are either good for maintaining planarity of the optical fibres in the ribbon for proper mass splicing or good for folding of the optical fibre ribbon in width direction for proper bundling but are not adequate for providing both functionalities to fulfil both requirements.
[0011] To overcome the aforementioned limitations of the current available intermittently bonded ribbons, the present invention proposes a pattern (bond sequence) of an intermittently bonded optical fibre ribbon with uniform matrix material density throughout the length of the optical fibre, with flexibility and improved folding characteristics for proper bundling and compact tubing, while maintaining the planarity of the ribbon in an optical fibre cable.

OBJECTIVE OF THE INVENTION
[0012] The prime objective of the present invention is to provide an intermittently bonded optical fibre ribbon comprises a plurality of optical fibres arranged in parallel in a length direction. The optical fibre ribbon has bonded portions and unbonded portions between each pair of the optical fibres in a width direction. The bonded portion is a portion of matrix material to bond any two adjacent optical fibre and the unbonded portion is a distance between the two bonded portions in any two adjacent optical fibre. The optical fibre ribbon has atleast one and utmost two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon. When there is a bond between any two optical fibres, then there is atleast a 5 mm distance between the next bond in the adjacent pairs of optical fibre.
[0013] Another objective of the present invention is to provide the intermittently bonded optical fibre ribbon with exactly two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon.
[0014] Another objective of the present invention is to provide the intermittently bonded optical fibre ribbon which has a uniform matrix material density throughout the length of optical fibre ribbon.
[0015] Another objective of the present invention is to provide the intermittently bonded optical fibre ribbon, which has the bonded portions, either with the same bond length or with the bond length of more than one size.
[0016] Another objective of the present invention is to provide the intermittently bonded optical fibre ribbon with a bond distance of atleast 5 mm, which makes the ribbon more flexible and helps in folding the ribbon in the width direction as well.
[0017] Another objective of the present invention is to provide the intermittently bonded optical fibre ribbon with improved folding characteristics.
[0018] All the objects of the present invention will be apparent from the drawings and descriptions herein. Every object of the invention is attained by at least one embodiment of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0019] The drawings described herein are for illustrative purposes for selected embodiments only and not all possible implementations. The amount of details offered are not intended to limit the scope of the present disclosure. Further objectives and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawing and wherein:
[0020] FIG. 1 depicts an illustrative view of the proposed bond pattern in an intermittently bonded optical fibre ribbon, having exactly two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon, in which the bond length is constant for the entire length of intermittently bonded optical fibre ribbon;
[0021] FIG. 2 depicts an illustrative view of the proposed pattern in an intermittently bonded optical fibre ribbon, having exactly two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon, in which the bond length has more than one value for the entire length of intermittently bonded optical fibre ribbon;
[0022] FIG. 3 depicts an illustrative view of the proposed pattern in an intermittently bonded optical fibre ribbon, having utmost two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon, in which the bond length is constant for the entire length of intermittently bonded optical fibre ribbon; and
[0023] FIG. 4 depicts an illustrative view of the proposed pattern in an intermittently bonded optical fibre ribbon, having utmost two bonded portions in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon in which the bond length has more than one value for the entire length of intermittently bonded optical fibre ribbon.
[0024] It will be recognized by the person of ordinary skill in the art, given the benefit of the present disclosure, that the examples shown in the figures are not necessarily drawn to scale. Certain features or components may have been enlarged, reduced or distorted to facilitate a better understanding of the illustrative aspects and examples disclosed herein. Also, the use of shading, patterns, dashes and the like in the figures is not intended to imply or mean any particular material or orientation unless otherwise clear from the context.

DETAILED DESCRIPTION OF THE INVENTION
[0025] The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting.
[0026] In any embodiment described herein, the open-ended terms "comprising," "comprises,” and the like (which are synonymous with "including," "having,” and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of," consists essentially of," and the like or the respective closed phrases "consisting of," "consists of, and the like.
[0027] As used herein, the singular forms “a”, “an” and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.
[0028] The present invention discloses an intermittently bonded optical fibre ribbon, which has a uniform matrix material density throughout the length of the optical fibre ribbon while maintaining the planarity of the ribbon. Thus, the present invention provides a novel pattern (P) of bonds (104) in an intermittently bonded optical fibre ribbon (100) with uniform matrix material density, having flexibility and folding characteristics. The length of the one pattern (P) of bonds sequence in the longitudinal direction is in the range of 30 mm to 360 mm. The same pattern repeats throughout the length of the optical fibre ribbon (100). Based on the length of the bonds (104) the length of the pattern (P) may vary.
[0029] The preferred embodiment of the present invention is directed towards the intermittently bonded optical fibre ribbon (100). The intermittently bonded optical fibre ribbon consists of a plurality of optical fibres. The plurality of optical fibres having a diameter in the range of 180um to 265 um (102) and are arranged in parallel. The optical fibre ribbon (100) has a length direction and a width direction whereas the width of the ribbon is (N x Fiber diameter) ± 50um, where ‘N’ represents the number of fibres used to make intermittently bonded ribbon(100). In a length direction, the optical fibre ribbon (100) has bonded portions (104) and unbonded portions (106) between each pair of the optical fibres (102). The bonded portion (104) is a length (L) of a matrix material between any two adjacent optical fibre (102) used to bond the optical fibres (102), and the unbonded portion (106) is a bond distance (D) between the two bonded portions (104). There is atleast one and utmost two bonded portions (104) in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon (100). When there is a bond (104) between a pair of fibre then there is atleast 5 mm distance (d) between the next bond (104) in the adjacent pair of fibre, which makes the ribbon more flexible and helps in folding the optical fibre (102) in the width direction as well. The optical fibre (102) has a diameter in the range of 180 micrometres to 265 micrometres.
[0030] Another aspect of the present invention is directed towards the intermittently bonded optical fibre ribbon (100), which consists of the plurality of optical fibres (102). There are exactly two bonded portions (104) in the width direction at any location along the length direction of the intermittently bonded optical fibre ribbon (100), resulting in the uniform density of the matrix material throughout the length of the optical fibre ribbon.
[0031] Another aspect of the present invention is directed towards the intermittently bonded optical fibre ribbon (100) which does not have any location along the length direction, with less than one bonded portion (104) and greater than two bonded portions (104) in the width direction.
[0032] Another aspect of the present invention is directed towards the bond length (L) of the matrix material between any two adjacent optical fibre (102). All the bonded portions (104) either have the bond length (L) of the same size or have the bond length (L) of more than one size. The bond length (L) of the matrix material between any two adjacent optical fibre (102) is in the range of 5 mm to 30 mm.
[0033] Another aspect of the present invention is directed towards the bond distance (D) of the intermittently bonded optical fibre ribbon (100). The distance (D) between two bonded portions (104) at any pair of fibres (102) is in the range of 5 mm to 180 mm. For a bonded portion (104) between any pair of the fibres (102), there is atleast 5 mm distance (d) between the next bonded portion (104) in the adjacent pair of the fibre (102), which makes the ribbon more flexible and helps in folding the ribbon in the width direction as well. For example, if there is a bonded portion (104) between the sixth and seventh fibres (102), then there will be atleast 5 mm distance (d) in the next bonded portion (104) in between the fifth and sixth fibres (104) and in between seventh and eighth fibres (102).
[0034] FIG. 1 shows an embodiment of the bonding pattern (P) in an intermittently bonded optical fibre ribbon (100), which has a constant bond length (L) for the entire length of the ribbon. The length of the one pattern (P) of bonds sequence in the longitudinal direction is in the range of 60 mm to 360 mm. The same pattern is repeated throughout the length of the optical fibre ribbon (100). Based on the length of the bonds (104) the length of the pattern (P) may vary.
[0035] In an exemplary embodiment, the length of the one pattern (P) of bonds sequence in the longitudinal direction is 180 mm. The intermittently bonded optical fibre ribbon (100) has a bond length (L) of 15 mm. The bond distance (D) in the intermittently bonded optical fibre ribbon (100) is in the range of 10 mm to 75 mm. At any location along the length direction of the intermittently bonded optical fibre ribbon (100), it has exactly two bonded portions (104) in the width direction so that the density of the matrix material is uniform throughout the length of the optical fibre ribbon.
[0036] Further, in an intermittently bonded optical fibre ribbon (100), when there is a bond (104) between any pair of fibres (102), then there is atleast 10 mm distance (d) between the next bond in the adjacent pair of fibre.
[0037] FIG. 2 shows an embodiment of the bonding pattern (P) in an intermittently bonded optical fibre ribbon (100) for the bond length (L) has a more than one value (more than one size), which is repeated for the entire length of the ribbon. The length of the one pattern (P) of bonds sequence in the longitudinal direction is in the range of 60 mm to 360 mm. The same pattern is repeated throughout the length of the optical fibre ribbon (100). Based on the length of the bonds (104) the length of the pattern (P) may vary.
[0038] In an exemplary embodiment, the length of the one pattern (P) of bonds sequence in the longitudinal direction is 150 mm. The intermittently bonded optical fibre ribbon (100) has a bond length (L) of 10 mm (L1) and 15 mm (L2). The bond distance (D) in the intermittently bonded optical fibre ribbon (100) is in the range of 10 mm to 65 mm. At any location along the length direction of the intermittently bonded optical fibre ribbon (100), it has exactly two bonded portions (104) in the width direction so that the density of the matrix material is uniform throughout the length of the optical fibre ribbon.
[0039] Further, in an intermittently bonded optical fibre ribbon (100), when there is a bond (104) between any pair of fibres (102), then there is atleast 10 mm distance (d)between the next bond in the adjacent pair of fibre.
[0040] FIG. 3 shows an embodiment of the bonding pattern (P) in an intermittently bonded optical fibre ribbon (100), which has a constant bond length (L) for the entire length of the ribbon similar to FIG. 1. The length of the one pattern (P) of bonds sequence in the longitudinal direction is in the range of 30 mm to 180 mm. The same pattern is repeated throughout the length of the optical fibre ribbon (100). However, in a pattern (P), at any location along the length direction of the intermittently bonded optical fibre ribbon (100), there is atleast one bonded portion (104) and utmost two bonded portions (104) in the width direction to make the ribbon more flexible for folding in the width direction.
[0041] In an exemplary embodiment, the length of the one pattern (P) of bonds sequence in the longitudinal direction is 90 mm. The intermittently bonded optical fibre ribbon (100) has a bond length (L) of 15 mm. The bond distance (D) in the intermittently bonded optical fibre ribbon (100) is 75 mm. At any location along the length direction of the intermittently bonded optical fibre ribbon (100), it has atleast one bonded portion (104) and utmost two bonded portions (104) in the width direction so that to make the ribbon more flexible for folding in the width direction.
[0042] Further, in an intermittently bonded optical fibre ribbon (100), when there is a bond (104) between any pair of fibres (102), then there is atleast 15 mm distance (d)between the next bond in the adjacent pair of fibre.
[0043] FIG. 4 shows an embodiment of the bonding pattern (P) in an intermittently bonded optical fibre ribbon (100) for the bond length (L) has a more than one value (more than one size), which is repeated for the entire length of the ribbon similar to FIG. 2. The length of the one pattern (P) of bonds sequence in the longitudinal direction is in the range of 30 mm to 180 mm. The same pattern is repeated throughout the length of the optical fibre ribbon (100). However, in a pattern (P), at any location along the length direction of the intermittently bonded optical fibre ribbon (100), there is atleast one bonded portion (104) and utmost two bonded portions (104) in the width direction to make the ribbon more flexible for folding in the width direction.
[0044] In an exemplary embodiment, the length of the one pattern (P) of bonds sequence in the longitudinal direction is 75 mm. The intermittently bonded optical fibre ribbon (100) has a bond length (L) of 15 mm. The bond distance (D) in the intermittently bonded optical fibre ribbon (100) is 65 mm. At any location along the length direction of the intermittently bonded optical fibre ribbon (100), it has atleast one bonded portion (104) and utmost two bonded portions (104) in the width direction so that to make the ribbon more flexible for folding in the width direction.
[0045] Further, in an intermittently bonded optical fibre ribbon (100), when there is a bond (104) between any pair of fibres (102), then there is atleast 5 mm distance (d) between the next bond in the adjacent pair of fibre.
,CLAIMS:1. An intermittently bonded optical fibre ribbon comprising:
- a plurality of optical fibres (1) arranged parallel in a length direction (2) ;
- atleast one bonded portion (3) and atleast one unbonded portion (4) between each adjacent pairs of the optical fibres (1) in a width direction (5); and
- a bond distance (6) between the two bonded portions (3) in an adjacent pair of the optical fibres (1); and
- a bond length (7) of a matrix material between any two adjacent pair of the optical fibre (1),
wherein there is atleast one and atmost two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon, and for the bonded portion (3) between any two pair of the fibres (1), there is atleast 10 mm distance in the next bonded portion (3) in the adjacent pair of the fibre (1).
2. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein there is exactly two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon.
3. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein the bond distance (6) is in the range of 10 mm to 180 mm.
4. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein the bond length (7) is in the range of 5 mm to 30 mm.
5. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein there is no location in the length direction (2) of the ribbon, with less than one bond portion (3) in the width direction (5).
6. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein there is no location in length direction (2) of the ribbon, with greater than two bond portions (3) in the width direction (5).
7. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein for exactly two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon, all the bonded portions (3) have the bond length (7) of same size in the range of 5 mm to 30 mm.
8. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein for exactly two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon, bonded portions (3) have the bond length (7) in combination of more than one size in the range of 5 mm to 30 mm.
9. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein for atmost two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon, all the bonded portions (3) have the bond length (7) of same size in the range of 5 mm to 30 mm.
10. The intermittently bonded optical fibre ribbon as claimed in claim 1, wherein for atmost two bonded portion (3) in the width direction (5) at any longitudinal position in the length direction (2) of the ribbon, bonded portions (3) have the bond length (7) in combination of more than one size in the range of 5 mm to 30 mm.