Patent Description:
Optical fibers are very small diameter glass strands capable of transmitting an optical signal over great distances, at very high speeds, and with relatively low signal loss relative to standard copper wire networks. Optical cables are therefore widely used in long distance communication and have replaced other technologies such as satellite communication, standard wire communication etc. Besides long distance communication, optical fibers are also used in many applications such as medicine, aviation, computer data servers, etc..

There is a growing need in many applications for optical cables that are able to transfer high data rates while taking minimum space. Such need can arise, for example, in data servers where space for the optical fiber is a critical limiting factor. In particular, data servers are processing increasingly higher amounts of data that require increased connectivity to the data servers. With the dramatic increase of data capacity among data centers all over the world due to expanding of crowd computing, the demand for high-fiber-count and high density optical cable increases. However, the maximum size of the optical cable is limited by the size of the ducts through which the cables have to be passed through. Squeezing the conventional optical cables through the ducts is not a viable option. This is because while conventional optical fibers can transmit more data than copper wires, they are also more prone to damage during installation. The performance of optical fibers within the cables is very sensitive to bending, buckling, or compressive stresses. Excessive compressive stress during manufacture, cable installation, or service can adversely affect the mechanical and optical performance of conventional optical fibers. Therefore, there is a need to reduce the diameter and weight of the cable. Decreasing cable diameter and weight will make it possible to use existing facilities such as underground ducts or telephone pole, and will reduce cable cost and installation cost.

In addition, to shorten the operation time of mid-span access or cable connection, the cable structure having easy workability is required.

<CIT> relates to a rollable optical fibre ribbon comprising a plurality of optical transmission elements, and a ribbon body coupled to and supporting the plurality of optical transmission elements in an array, wherein the ribbon body is contiguous lengthwise along the length of the plurality of optical transmission elements and is contiguous widthwise over the plurality of optical transmission elements; wherein the ribbon body is formed from a flexible polymeric material such that the plurality of optical transmission elements are reversibly movable from an unrolled position in which the plurality of optical transmission elements are substantially aligned with each other to a rolled position. <CIT> relates to a splittable optical-fibre ribbon product comprising a first sub-unit comprising a first plurality of optical fibres arranged substantially in a plane and encapsulated in a first matrix material, a second sub-unit comprising a second plurality of optical fibres arranged substantially in a plane and encapsulated in a second matrix material, the first sub-unit and the second sub-unit being disposed adjacent to one another so that the first plurality of optical fibres and the second plurality of optical fibres lie substantially in one plane, bonding material disposed on the first sub-unit and on the second sub-unit so as not to fully encapsulate both of the first sub-unit and the second sub-unit. <CIT> relates to an optical fibre tape core wire in which a plurality of optical fibres are arranged in parallel, and adjacent optical fibres are intermittently connected in a longitudinal direction, and a connecting resin is continuously formed across at least two adjacent optical fibres. <CIT> relates to an optical fibre ribbon comprising a plurality of optical fibres, a matrix being a radiation curable material, the matrix connecting the plurality of optical fibres, thereby forming the optical fibre ribbon, wherein the optical fibre ribbon includes at least one preferential tear portion formed by a weakened portion in the matrix, the weakened portion of the matrix having a reduced cure level compared with the surrounding matrix material, thereby creating the weakened portion.

<CIT> relates to an optical fibre unit in which a bundled body made of a set of a plurality of optical fibres is bundled with a bundle material, wherein the bundle material is vertically arranged in a width direction with respect to the constituent elements of the bundled body arranged in parallel.

<CIT> relates to an optical fiber ribbon and a method of producing the same. This document is only relevant for the purposes of Article <NUM>(<NUM>) EPC.

The present invention relates to an optical fiber cable according to claim <NUM>.

The present invention also relates to a method for forming an optical fiber cable according to claim <NUM>.

For a more complete understanding of the present application, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:.

The presently preferred embodiments, including their making and use, are discussed below in detail. These specific embodiments do not limit the scope of the invention which is defined in the appended claims.

The present application will be described by referring to exemplary embodiments in a specific context, namely the structure and making of unitized flexible ribbons comprising a plurality of optical fibers.

In various embodiments, unitized structures of flexible ribbons used in optical cables are disclosed. An optical cable includes many such ribbons, where each ribbon may be made of a number of optical fibers, for example, twelve to sixteen optical fibers. Embodiments of the present application describe joining flexible ribbons using a pattern of matrix materials so as to unitize the ribbons thereby forming an assembly of flexible ribbons. For example, two flexible ribbons of twelve optical fibers become a single unitized ribbon of twenty four optical fibers.

Embodiments of the present application provide an advantage in manufacturing cables of flexible ribbons as fewer independent components have to be stranded and injected into the cable during the ribbon buffering process. For example, embodiments of the present application can reduce the number of pay-off during ribbon buffering where a high number of ribbon bobbins are used for high fiber count cable. Due to the enhanced flexibility provided by the flexible ribbon assembly, more number of optical fibers can be packed within each buffer tube enabling higher fiber density. In addition, the user/installer of these cables will benefit due to a reduction in complexity. For example, when the user/installer removes the unitized ribbons or flexible ribbon assemblies from the buffer tube, fewer ribbons have to be handled and easier steps need to be taken for mass splicing of the optical fibers. As illustration, instead of exposing <NUM> flexible ribbons (each with twelve optical fibers) from a buffer tube, the user/installer will have to deal only with <NUM> unitized flexible ribbons with 2x12 optical fibers in each. This will be easier to get into the enclosure prior to splitting the ribbons and splicing the optical fibers.

A flexible optical ribbon assembly with a continuous bonding region between its component flexible optical ribbons will initially be described in top, bottom, and cross-sectional views in <FIG>. This is followed by descriptions of several additional structural embodiments of the flexible ribbon assembly, varying in the shapes and positions of the applied bonding regions between the component optical fibers, in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG>. An optical cable design implementing embodiments of the present application will be described using <FIG>. A method for making the unitized flexible optical ribbon will be described using <FIG> and <FIG>. All figures, except <FIG>, illustrate the flexible ribbons in rolled-out or planar configuration. In a cable, the flexible ribbons are rolled-up or wrapped together in buffer tubes as illustrated, for example, in <FIG>.

<FIG> illustrates an optical cable in accordance with an embodiment of the present application. <FIG> illustrates a top view of a unitized flexible ribbon of the optical cable. <FIG> illustrates a bottom view of the unitized flexible ribbon of the optical cable. <FIG> illustrates a corresponding cross-sectional area of the unitized flexible ribbon illustrated in <FIG>.

Referring to <FIG>, the optical cable includes a flexible ribbon assembly <NUM> comprising a plurality of flexible ribbons such as a first flexible ribbon <NUM> and a second flexible ribbon <NUM>. In various embodiments, a plurality of optical fibers is stacked or bunched together to form a single flexible ribbon. However, unlike conventional ribbons that are stacked and encapsulated together, in various embodiments, each of the optical fiber is attached loosely (in a non-rigid manner, without encapsulation) so that the ribbon maintains flexibility to be arranged in different shapes. For example, as illustrated in the cross-sectional view of <FIG>, the first flexible ribbon <NUM> includes a first set of optical fibers <NUM>-<NUM> while the second flexible ribbon <NUM> includes a second set of optical fibers <NUM>-<NUM>. Although only eight optical fibers are illustrated, in various embodiments, an individual flexible ribbon may include a greater or smaller number of optical fibers. For example, in one embodiment, the first and the second flexible ribbons <NUM> and <NUM> include six optical fibers. Yet, in another embodiment, the first and the second flexible ribbons <NUM> and <NUM> may include twelve or sixteen optical fibers. In other words, the number of optical fibers may vary depending on the application.

Referring to <FIG> and <FIG>, adjacent optical fibers are attached together at first bonding regions <NUM>. As best illustrated in <FIG>, the first bonding regions <NUM> fill the gaps between adjacent optical fibers such as the seventh optical fiber <NUM> and the eighth optical fiber <NUM>. In addition, the first bonding regions <NUM> are formed on the first side <NUM> of the first flexible ribbon <NUM> as opposed to the second side <NUM>.

Referring to <FIG>, adjacent first bonding regions <NUM> joining optical fibers are separated from each other by a first pitch p41. Although, the first pitch p41 does not vary within the cable as illustrated in <FIG>, in some embodiments, the first pitch p41 may not be constant within the cable. To maintain a constant pitch, the first bonding regions <NUM> has a duty cycle of <NUM>%, in other words, formed only during half the wave cycle. In other words, at a <NUM>% duty junction, only alternate intersections between adjacent optical fibers along the first pattern <NUM> have a bonding region. In case of a <NUM>% duty cycle, all intersections between adjacent optical fibers along the first pattern <NUM> have a bonding region.

The first pitch p41 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the first pitch p41 may vary from about <NUM> to about <NUM>.

The first bonding regions <NUM> extend into the page of <FIG> and as illustrated in <FIG> may have a first bond length b41. The first bond length b41 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the first bond length b41 may vary from about <NUM> to about <NUM>.

Each first bonding region <NUM> is separated from the nearest first bonding region joining different optical cables by a first neighbor distance n41.

In various embodiments, these distances (first pitch p41, first bonding length b41, and the first neighbor distance n41) will be varied to achieve a pre-determined set of mechanical properties of the ribbons such as strength, flexibility or rigidity and to achieve a target production cost and capability.

In addition, drawing a curve passing through the nearest neighboring regions of the first bonding regions <NUM> results in a first pattern <NUM>. In the illustration, and according to the invention, the first pattern <NUM> comprises a wave pattern. The wave pattern may be described using the first pitch p41, first bonding length b41, and the first neighbor distance n41. Alternately, the wave pattern may be described using the wavelength (first pitch p41) and a first amplitude a41 along with the first bonding length b41. In various embodiments, the wave pattern formed by the first bonding regions <NUM> may comprise any type of waves such as square waves, sine waves, cosine waves, triangular waves, and others.

However, in various embodiments, the first bonding regions <NUM> may be arranged in other patterns. Some of these alternate patterns will be described further in subsequent embodiments.

The first bonding regions <NUM> comprises a matrix material acting as the bonding agent between the adjacent optical fibers. According to the invention, the first bonding regions comprise a UV cured acrylate material. In comparative examples outside the subject-matter of the claims, the matrix material of the first bonding regions <NUM> may comprise a cured resin, or the first bonding regions <NUM> may comprise other bonding materials such as a thermoplastic material.

Referring to <FIG>, the first flexible ribbon <NUM> is attached to the second flexible ribbon <NUM> at a second bonding region <NUM>. According to the invention, the second bonding region <NUM> is formed on the second side <NUM>, opposite the first side <NUM> on which the first bonding regions <NUM> are formed. This is illustrated in <FIG>, where solid lines and white regions illustrate the first bonding regions <NUM> on the first side <NUM>. In contrast, dashed lines illustrate the second bonding region <NUM> on the second side <NUM>. In <FIG>, which gives a bottom view, the first pattern <NUM> of the first bonding regions <NUM> on the first side <NUM> is illustrated with dashed lines and the second bonding region <NUM> on the second side <NUM> is depicted with solid lines and white regions. This convention is maintained throughout the remaining figures. However, as will be clear from later description, the first side <NUM> and the second side <NUM> are not planes in an optical cable since the flexible ribbons are folded. In other words, the first side <NUM> and the second side <NUM> are in the same plane before being folded and incorporated into the cable. But once within the cable, the ribbon is folded and therefore the first side <NUM> and the second side <NUM> may not share a common plane.

<FIG> illustrate an embodiment in which the second bonding region <NUM> extends linearly and continuously between adjacent flexible ribbons such as the first flexible ribbon <NUM> and the second flexible ribbon <NUM>. As illustrated in <FIG>, the second bonding region <NUM> joins adjacent optical fibers of the first and the second flexible ribbons <NUM> and <NUM>. This is also illustrated in <FIG>, where the second bonding region <NUM> fills the gap between the eighth optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM> with the first optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM>.

In addition, the second bonding region <NUM> is formed on the second side <NUM> of the flexible ribbon assembly <NUM>, which is on the opposite side of the first bonding regions <NUM>. Accordingly, in this embodiment, the flexible ribbon assembly <NUM> comprises the first flexible ribbon <NUM> and the second flexible ribbon <NUM>, unitized by the linear, continuous second bonding region <NUM>.

However, in various embodiments, a plurality of second bonding regions <NUM> may be used instead of a single second bonding region, and the plurality of second bonding regions <NUM> may be arranged in other patterns. Some of these alternate patterns will be described further in subsequent embodiments.

Advantageously, as the bonding area of the plurality of second bonding regions <NUM> is much smaller than a conventional encapsulation that covers all the optical fibers, the flexible ribbon assembly <NUM> maintains a higher degree of flexibility. In addition, the smaller bonding area results in a smaller bond strength resulting in easier separability of the flexible ribbons in to smaller groups of two or three for mass fusion splicing. Preferably the bonding strength of the second bonding regions <NUM> is less than the bonding strength of the first bonding regions <NUM>. This creates a preferential separating between the flexible ribbons when the flexible ribbon assembly <NUM> is split in groups of two or three flexible ribbons for mass fusion splicing and prevents one or more fibers of one flexible ribbon to remain attached to the adjacent flexible ribbon. The bond strength of the second bonding regions <NUM> (as well as the first bonding regions <NUM>) may be adjusted by the length of the bonding regions, the degree of curing of the flexible ribbon surface, or the composition of the bonding material such as the presence or quantity of adhesion promotors.

In various embodiments, when measured using a technique such as a T-peel test , the bond strength of the first bonding regions <NUM> would be in the range of <NUM>. 1N to <NUM>. 5N, preferably between <NUM>. 1N and <NUM>. 3N, whereas the bond strength of the second bonding regions <NUM> (while being less than the bond strength of the first bonding regions) would be in the range of <NUM>. 01N to <NUM>. 3N, preferably between <NUM>. 01N and <NUM>.

In a T-peel test a single fiber, or a group of fibers from an end of the ribbon is clamped in a grip of the tensile tester (e.g. Instron <NUM>), while the remaining fibers from the same end of the ribbon are clamped in the opposite grip of the tensile tester and the force to separate both is measured. In such a T-peel test the force to break a single bond is measured.

<FIG> illustrate another embodiment of the present application in which the second bonding region <NUM> has a continuous wave pattern. <FIG> illustrates the first side <NUM> of the flexible ribbon assembly <NUM> with first bonding regions <NUM> applied in the first pattern <NUM> having a first pitch p41 as described using <FIG>. <FIG> illustrates the bottom surface of the flexible ribbon assembly <NUM> with the second bonding region <NUM> is formed continuously along a wavelike pattern.

In the embodiment illustrated by <FIG>, the second bonding region <NUM>, similar to the prior embodiment, comprises a first section S35-<NUM> that joins the eighth optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM> with the first optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM>. However, unlike the prior embodiment, the second bonding region <NUM> further comprises a second section S35-<NUM> and a third section S35-<NUM> that join adjacent optical fibers within the same flexible ribbon. For example, in the illustration, the second section S35-<NUM> joins the seventh optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM> with the eighth optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM>. Similarly, the third section S35-<NUM> joins the first optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM> with the second optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM>.

As illustrated in <FIG>, the second bonding region <NUM> has a shape of wave having a second amplitude a2. In other embodiments, second bonding region <NUM> may have a larger amplitude (than illustrated in <FIG>) so that more optical fibers are joined by the second bonding region <NUM>. In other words, as the second amplitude a2 of the continuous wave pattern increases, the second bonding region <NUM> will join together an increasing number of optical fibers in the first flexible ribbon <NUM> and the second flexible ribbon <NUM>.

In various embodiments, the shape formed by the second bonding regions <NUM> may comprise any type of waves such as square waves, sine waves, cosine waves, triangular waves, and others. In further embodiments, the shape formed by the second bonding regions <NUM> may be an arbitrary shape such as a "zigzag" shape.

<FIG> illustrates an optical cable in accordance with an embodiment of the present application in which the second bonding region has a larger width to join together multiple optical fibers. <FIG> illustrates a top view of a unitized flexible ribbon of the optical cable. <FIG> illustrates a bottom view of the unitized flexible ribbon of the optical cable. <FIG> illustrates a corresponding cross-sectional area of the unitized flexible ribbon illustrated in <FIG>.

In contrast to the embodiment of <FIG>, the second bonding region <NUM> is linear and continuous similar to the embodiment of <FIG>. However, unlike the embodiment described using <FIG>, in this embodiment, the second bonding region <NUM> is wider so as to join more optical fibers together.

Therefore, this embodiment may be similar to <FIG> in that a linear continuous second bonding region <NUM> is disposed on the second side <NUM> so as to join the first flexible ribbon <NUM> with the second flexible ribbon <NUM>. However, unlike the embodiment of <FIG>, in this embodiment, the second bonding region <NUM> may be wider having a width w35 that overlaps more than just two optical fibers. In the illustration, the second bonding region <NUM> has a width w35 that overlaps with the seventh optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM>, the eighth optical fiber <NUM> from the first set of optical fibers <NUM>-<NUM> of the first flexible ribbon <NUM>, the first optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM>, and the second optical fiber <NUM> from the second set of optical fibers <NUM>-<NUM> of the second flexible ribbon <NUM>.

The second bonding region <NUM> may also be thicker so that a partial encapsulation of a plurality of optical fibers is achieved. While this embodiment may not be as flexible as the embodiment of <FIG>, the partial encapsulation provided by the second bonding region <NUM> may have an improved mechanical strength favored in some applications.

<FIG> illustrates a unitized flexible ribbon of an optical cable in accordance with an embodiment of the present application. <FIG> illustrates a top view of a unitized flexible ribbon comprising intermittent bonding regions, and <FIG> illustrates a bottom view of the unitized flexible ribbon illustrating the intermittent bonding regions.

In further embodiments, the second bonding region <NUM> may be applied in a manner similar to the first bonding regions <NUM> described in the prior embodiments. In other words, instead of a continuous second bonding region <NUM> (as described in <FIG> above), a plurality of second bonding regions <NUM> may be used to form an flexible ribbon assembly <NUM>. Each bonding region of the plurality of second bonding regions <NUM> is shorter than the length of individual optical fibers.

Referring to <FIG>, in one embodiment, the first flexible ribbon <NUM> and the second flexible ribbon <NUM> are joined together on the second side <NUM>. <FIG> illustrates that the plurality of second bonding regions <NUM> is applied between the adjacent optical fibers of the first flexible ribbon <NUM> and the second flexible ribbon <NUM>.

The plurality of second bonding regions <NUM> may have a second bond length b42 as illustrated in <FIG>. The second bond length b42 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the second bond length b42 may vary from about <NUM> to about <NUM>.

In the embodiment illustrated by <FIG>, adjacent bonding regions of the plurality of second bonding regions <NUM> are separated by a second pitch p42. The second pitch p42 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the second pitch p41 may vary from about <NUM> to about <NUM>. In one embodiment, the second pitch p41 varies from <NUM> to <NUM>.

In addition, drawing a curve passing through the nearest neighboring regions of the second bonding regions <NUM> results in a second pattern <NUM>. As illustrated in <FIG>, the second pattern <NUM> comprises a wave pattern. Similar to the first pattern <NUM>, the second pattern <NUM> may also alternatively be described using the second pitch p42, and the second bond length b42.

In various embodiments, these distances (second pitch p42 and second bonding length b42) will be varied to achieve a pre-determined set of mechanical properties of the flexible ribbon assembly <NUM> such as strength, flexibility or rigidity and to achieve a target production cost and capability.

<FIG> illustrates a unitized flexible ribbon of an optical cable in accordance with an alternative embodiment of the present application, wherein <FIG> illustrates a top view of a unitized flexible ribbon comprising intermittent bonding regions having an alternative pattern than <FIG>, and wherein <FIG> illustrates a bottom view of the unitized flexible ribbon illustrating the intermittent bonding regions;.

Unlike the prior embodiment of <FIG>, in this embodiment, the plurality of second bonding regions <NUM> is arranged as a wave so as to join together more than two optical fibers. Referring to <FIG>, in one embodiment, the plurality of second bonding regions <NUM> follows a third pattern <NUM>.

Referring to <FIG>, adjacent plurality of second bonding regions <NUM> joining the same optical fibers are separated from each other by a third pitch p43. To maintain a constant pitch, the plurality of second bonding regions <NUM> has a duty cycle of <NUM>%, in other words, formed only during half the wave cycle. The third pitch p43 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the third pitch p43 may vary from about <NUM> to about <NUM>. In one embodiment, the third pitch p43 varies from <NUM> to <NUM>.

The plurality of second bonding regions <NUM> includes a first discrete region R1, a second discrete region R2. The first discrete region R1 and the second discrete region R2 join a last optical fiber (eighth optical fiber <NUM>) of the first flexible ribbon <NUM> with a first optical fiber <NUM> of the second flexible ribbon <NUM>. The first discrete region R1 and the second discrete region R2 are disposed at a first intersecting region and a second intersecting region between the last optical fiber and the first optical fiber <NUM>. The second discrete region R2 is spaced from the first discrete region R1 by the third pitch p43.

Unlike the prior embodiment, in this embodiment, the plurality of second bonding regions <NUM> includes a third discrete region R3 connecting other optical fibers. The third discrete region R3 joins the first optical fiber <NUM> of the second flexible ribbon <NUM> with the second optical fiber <NUM> of the second flexible ribbon <NUM> and is disposed at a third intersecting region between the first optical fiber <NUM> and the second optical fiber <NUM>.

Each of the plurality of second bonding regions <NUM> may have a third bond length b43. The third bond length b43 may vary, for example, from about <NUM> to about <NUM> depending on the application. In one or more embodiments, the third bond length b43 may vary from about <NUM> to about <NUM>. In the illustrated embodiment of <FIG> and <FIG>, the first bond length b41 is substantially the same as the third bonding length b43.

Each of the plurality of second bonding regions <NUM> is separated from the nearest second bonding region joining different optical cables by a third neighbor distance n43. In various embodiments, these distances (third pitch p43, third bonding length b43, and the third neighbor distance n43) will be varied to achieve a pre-determined set of mechanical properties of the ribbons such as strength, flexibility or rigidity and achieving a target production cost and capability.

In addition, drawing a curve passing through the nearest neighboring regions of the plurality of second bonding regions <NUM> results in a third pattern <NUM>. In the illustration, the third pattern <NUM> comprises a wave pattern. The wave pattern of the third pattern <NUM> may be described using the third pitch p43, third bonding length b43, and the third neighbor distance n43. Alternately, the wave pattern may be described using the wavelength (third pitch p43) and a third amplitude a43 along with the third bonding length b43. In various embodiments, the pattern formed by the second bonding regions <NUM> may comprise any type of waves such as square waves, sine waves, cosine waves, triangular waves, and others.

In the embodiment illustrated in <FIG>, the third pattern <NUM> has the same phase as the first pattern <NUM> and the third pitch p43 has the same pitch as the first pitch p41 of the first pattern <NUM> that describes the first bonding regions <NUM> on the first side <NUM> of the flexible ribbon assembly <NUM>. Additionally, in this embodiment, the third amplitude a43 of the third pattern <NUM> is less than the first amplitude a41 of the first pattern <NUM>. In other embodiments, the third amplitude a43 of third pattern <NUM> may be varied to achieve different properties of the flexible ribbon assembly <NUM> such as flexibility or bonding strength.

<FIG> illustrates a unitized flexible ribbon of an optical cable in accordance with an alternative embodiment of the present application, wherein <FIG> illustrates a top view of a unitized flexible ribbon comprising intermittent bonding regions having yet another alternative pattern, wherein <FIG> illustrates a bottom view of the unitized flexible ribbon illustrating the intermittent bonding regions, and wherein <FIG> illustrates a bottom view of the unitized flexible ribbon illustrating the intermittent bonding regions in an alternative embodiment;.

This embodiment may be similar to the embodiment described using <FIG>, except that the plurality of second bonding regions <NUM> is arranged in a different wave pattern illustrated schematically as the fourth pattern <NUM>. In particular, in this embodiment, the fourth pattern <NUM> has the same phase, pitch, and amplitude as first pattern <NUM>. Therefore, as illustrated in <FIG>, the first amplitude a41 is the same as the fourth amplitude, while the first pitch p41 is the same as the fourth pitch p44.

In contrast to <FIG>, in <FIG>, the fourth pattern <NUM> has the same pitch and amplitude as the first pattern <NUM>. However, relative to the first pattern <NUM> (illustrated, for example, in <FIG>), the duty cycle has a phase difference. This is also evident from comparing <FIG> and <FIG>, the duty cycle of the embodiment of <FIG> has a <NUM>° phase difference with the duty cycle of the embodiment of <FIG>.

As a further illustration, the first bonding regions <NUM> on the first side <NUM> and the second bonding regions <NUM> on the second side <NUM> of the embodiment of <FIG> have different bonding lengths. In the illustrated embodiment of <FIG> and <FIG>, the first bond length b41 is substantially different from the fourth bonding length b44. In one embodiment as illustrated in <FIG>, the fourth bonding length b44 is longer than the first bonding length b41, for example, by <NUM>%. In another embodiment, the fourth bonding length b44 is shorter than the first bonding length b41.

<FIG> illustrates a unitized flexible ribbon of an optical cable in accordance with an alternative embodiment of the present application, wherein <FIG> illustrates a top view of a unitized flexible ribbon comprising intermittent bonding regions having yet another alternative pattern, and wherein <FIG> illustrates a bottom view of the unitized flexible ribbon illustrating the intermittent bonding regions;.

In contrast to the prior embodiments, in this embodiment, the bonding regions are arranged with a <NUM>% duty cycle. See, for example, the first bonding regions <NUM> on the first side <NUM> of the flexible ribbon assembly <NUM> in <FIG> and the second bonding regions <NUM> on the second side <NUM> of the flexible ribbon assembly <NUM> in <FIG>. Consequently, due to the wave like pattern of the first pattern <NUM> and the fifth pattern <NUM>, in this embodiment, the optical fibers in the central region of the flexible are more rigidly attached than the optical fibers at the outer periphery of the wave pattern. For example, as a consequence, the attachment between the first flexible ribbon <NUM> and the second flexible ribbon <NUM> may be stronger at the point of intersection between these ribbons. In a further embodiment, the first bonding regions <NUM> may be arranged at a duty cycle of <NUM>% (e.g., as in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>) while the second bonding regions may be arranged at a duty cycle of <NUM>%.

In addition, the fifth pattern <NUM> illustrated in <FIG> may have a different phase from the first pattern <NUM> illustrated in <FIG> while retaining the similar pitch and amplitude as the first pattern <NUM>.

<FIG> illustrate top views of an unitized flexible ribbon in accordance with various alternative embodiments of the present application. A corresponding bottom view is not illustrated but the dashed lines illustrate the features on the opposite side.

Referring to <FIG>, a plurality of second bonding regions <NUM> is arranged in another alternative sixth pattern <NUM>. For clarity only a few of the plurality of second bonding regions <NUM> are illustrated in <FIG>.

The sixth pattern <NUM> has a larger amplitude than those illustrated in earlier embodiments so that a plurality of second bonding regions <NUM> is applied across the junctions of every (or almost all) optical fiber on the bottom side of the flexible ribbon assembly <NUM>. In this embodiment, the first bond length b41 of the first bonding regions <NUM> may be substantially equal to the sixth bond length b46 of the second bonding regions <NUM>. In other embodiments, the first bond length b41 of the first bonding regions <NUM> may be different from the sixth bond length b46 of the second bonding regions <NUM>. Although the first bonding regions <NUM> are arranged with a duty cycle of <NUM>% along the first pattern <NUM>, in other embodiments, a different duty cycle may be chosen. Some options include <NUM>%, <NUM>%, and <NUM>%.

<FIG> illustrates an additional alternative embodiment of the present application with a "zigzag" pattern. Referring to <FIG>, a plurality of second bonding regions <NUM> is arranged in another alternative seventh pattern <NUM>. Again, for clarity only a few of the plurality of second bonding regions <NUM> are illustrated in <FIG>.

In one embodiment, the seventh pattern <NUM> may have a large amplitude so that the intersecting junctions of every (or almost all) optical fibers on the bottom side of the flexible ribbon assembly <NUM> is attached using one of the plurality of second bonding regions <NUM>. In <FIG>, the seventh pattern <NUM> traverses the entire width of the flexible ribbon assembly <NUM>.

In one embodiment, the first bond length b41 of the first bonding regions <NUM> may be substantially equal to the seventh bond length b47 of the second bonding regions <NUM>. In other embodiments, the first bond length b41 of the first bonding regions <NUM> may be different from the seventh bond length b47 of the second bonding regions <NUM>. Additionally, other embodiments may comprise further alternative irregular zigzag patterns describing the application of the plurality of second bonding regions <NUM>.

Alternatively, as illustrated in <FIG>, in other embodiments, the pattern of the plurality of second bonding regions <NUM> may have a smaller amplitude than illustrated in <FIG>. Accordingly, the eighth pattern <NUM> only covers a portion of the width of the flexible ribbon assembly <NUM>. As illustrated, the eighth bond length b48 may be larger than the first bond length b41 in one embodiment.

As <FIG> illustrate, the seventh and eighth patterns <NUM> and <NUM> do not have a proper wave shape or a repeating triangular shape. Accordingly, in various embodiments, second bonding regions <NUM> may be applied intermittently by other irregular patterns with varying amplitudes, pitches, and phases.

<FIG> illustrates another alternative embodiment of the present application wherein the second bonding regions <NUM> are applied intermittently on the second side <NUM> of the flexible ribbon assembly <NUM> forming a wavelike ninth pattern <NUM>. As the figure illustrates, the ninth pattern <NUM> has a constant phase difference with the first pattern <NUM> on the first side <NUM>. In the illustrated embodiment, the duty cycle of the ninth pattern <NUM> is <NUM>% although other values are possible in other embodiments.

<FIG> illustrates another alternative embodiment of the present application wherein the second bonding regions <NUM> are applied intermittently on the second side <NUM> of the flexible ribbon assembly <NUM> forming a square wave. In various embodiments, the pattern formed by the second bonding regions <NUM> may comprise any type of waves such as square waves, sine waves, cosine waves, triangular waves, and others. For illustration, a square wave is used in <FIG>. The second bonding regions <NUM> are arranged at <NUM>% duty cycle for illustration alternating between the intersecting regions.

<FIG> illustrate the application of embodiments of the present application to the formation of optical cables. Although any type of optical cable may use the unitized flexible ribbon, one illustrated is provided using <FIG>. Accordingly, <FIG> illustrates a folded unitized flexible ribbon, while <FIG> illustrates a cross-sectional view of a buffer tube formed using a plurality of flexible ribbon assemblies and <FIG> illustrates a cross-sectional view of the optical cable comprising a plurality of buffer tubes of <FIG>.

Referring to <FIG>, as described in various embodiments above, a plurality of optical fibers are arranged parallel to each other and are connected at first bonding regions <NUM> and second bonding regions <NUM>. As previously discussed, the first and second bonding regions <NUM> and <NUM> are arranged intermittently across the flexible ribbons so as to selectively leave a large surface of the optical cables free of the bonding material. Consequently, the plurality of optical fibers maintains a large degree of freedom and can be effectively folded or otherwise randomly positioned when the ribbon is subjected to external stress.

In various embodiments, the plurality of optical fibers can be folded into a densely packed configuration. In one or more embodiments, the folded optical fibers may have a non-circular or irregular shape. In contrast, ribbons that are encapsulated cannot be folded efficiently due to their excessive rigidity.

<FIG> illustrates a buffer tube comprising a plurality of flexible ribbon assemblies in accordance with an embodiment of the present application. In one embodiment, the buffer tube may be a deformable buffer tube that has been deformed during the formation of the optical cable. In other embodiments, the buffer tube may be a non-deformable buffer tube that maintains a circular shape with the optical cable.

The flexible ribbon assemblies <NUM> comprise two or more flexible ribbons formed as described in various embodiments above. The flexible ribbon assemblies <NUM> are enclosed by a buffer tube jacket <NUM>. In one or more embodiments, the buffer tube jacket <NUM> comprises polypropylene, cellular polypropylene, polyethylene, nylon, or other materials.

In addition, the flexible ribbon assemblies <NUM> may be dispersed within a gel <NUM> that allows the flexible ribbon assemblies <NUM> to move around relative to each other. Further, the thickness of the buffer tube jacket <NUM> is maintained to enable the flexibility of the ribbons.

During the formation of the optical cable, the buffer tube may be subjected to compressive stress. Buffer tubes may show increased deformation under an equivalent stress due to the temperature dependent modulus reduction during jacketing. As a consequence, the flexible ribbon assemblies <NUM> within the buffer tube <NUM> may rearrange the shape/configuration to compensate or minimize this compressive stress.

The rearrangement of the flexible ribbon assemblies <NUM> within the optical cable does not result in twisting or bending of the optical fibers. Therefore, embodiments of the present application achieve improved packing density without compromising on mechanical or optical characteristics of the optical cable.

The foldable flexible ribbon assemblies <NUM> are run lengthwise along each buffer tube <NUM>, and each flexible ribbon such as the first flexible ribbon <NUM> and the second flexible ribbon <NUM> is allowed to take a random configuration. Subsequent twisting, if any, of the plurality of buffer tubes <NUM> while forming the cable is sufficient to average strain across the optical fibers and meet mechanical and optical standards for the fiber optic cable.

Although, in <FIG>, only two flexible ribbon assemblies <NUM> are shown to be within the buffer tube <NUM>, in various embodiments, the buffer tube <NUM> may include a much larger or even a smaller number of flexible ribbon assemblies <NUM>. For example, in one embodiment, the buffer tube <NUM> may comprise twelve or twenty four flexible ribbon assemblies <NUM>. In addition, each of the flexible ribbon assemblies <NUM> may include any suitable number of flexible ribbons such as the first flexible ribbon <NUM> and the second flexible ribbon <NUM>. Each flexible ribbon may similarly have any number of optical fibers. The optical fibers may have a diameter in the range of <NUM> to <NUM> in various embodiments. For example, each of the flexible ribbons may include twelve optical fibers in one illustration. Therefore, in this example, the buffer tube <NUM> includes <NUM> or <NUM> optical fibers.

<FIG> illustrates a cross-sectional view of an optical cable implementing embodiments of the present application.

Embodiments of the present application may be implemented in many types of optical cables. However, for illustration, a particular optical cable is illustrated. Referring to <FIG>, the optical cable includes a rigid central strength member <NUM>. An upjacket <NUM> surrounds the central strength member <NUM>. The outer cover <NUM> of the optical cable may include several layers such as a water blocking layer <NUM>, and an optional outer strength member <NUM> that may include a steel armor, and an outer jacket <NUM>.

The optical cable further includes buffer tubes <NUM> that contain multiple flexible ribbon assemblies <NUM> comprising a plurality of optical fibers. The flexible ribbon assemblies <NUM> are arranged into a buffer tube <NUM> as previously described. The buffer tube <NUM> may have a rigid round shape or may be a deformable buffer tube that conforms to the shape of the arrangement of the flexible ribbon assemblies <NUM>. The space <NUM> between the buffer tubes <NUM> may be void or alternately filled with a suitable fill material.

In various embodiments, the optical cable may be designed to be compatible with one or more standards.

<FIG> illustrate a unitized flexible ribbon during various stages of fabrication in accordance with embodiments of the present application featuring a method with a moving ribbon or ribbon assembly.

<FIG> illustrates a schematic system diagram illustrating the formation of a flexible ribbon from a plurality of optical fibers in accordance with embodiments of the present invention.

A plurality of optical fibers <NUM> (individual optical fibers such as the first set of optical fibers <NUM>-<NUM>) are paid off from reels and fed, into a first die <NUM>, providing a longitudinal optical fiber assembly <NUM> so that the plurality of optical fibers <NUM> are in parallel and adjacent to each other. The arrow direction shows the motion of the optical fibers <NUM> during the processing.

A first dispensing device <NUM> applies a bonding material, such as an UV curable resin, to the surface of the optical fiber assembly <NUM> at the first side <NUM>. The bonding material may also be a thermoplastic material so that the first dispensing device <NUM> applies a thread of the thermoplastic material to the surface of the optical fiber assembly <NUM>. For example, the thermoplastic material may be heated to above its softening point and formed into a thread, and the softened thermoplastic thread may be applied to the surface of the optical fiber assembly <NUM>. After cooling, the applied thermosplastic thread forms the first bonding regions described in various embodiments.

When a curing process is desired, the optical fiber assembly <NUM> with the applied bonding material is then passed through a first curing station <NUM>, and thereafter the flexible ribbon assembly <NUM> is then picked up on a pick-up reel <NUM>.

<FIG> illustrates a magnified view of the plurality of flexible ribbons in the method described above in <FIG>.

Referring to <FIG>, a plurality of flexible ribbons such as the first flexible ribbon 50is formed, for example, sequentially. As illustrated, the first set of optical fibers <NUM>-<NUM> are paid off from reels and positioned parallel to each other on a first moving carrier <NUM>. The first moving carrier <NUM> may comprise a conveyer belt, or any other suitable construction. Alternately, the first set of optical fibers <NUM>-<NUM> may be suspended freely while being supported by rollers, which may also provide the translational movement of the optical fibers along their length.

Each of the first set of optical fibers <NUM>-<NUM> are arranged parallel to each other during this process, for example, extending into the plane of paper in <FIG>. The first set of optical fibers <NUM>-<NUM> have a first side <NUM> facing away from the first moving carrier <NUM>.

The first moving carrier <NUM> with the parallel optical fibers <NUM>-<NUM> arranged on top of it is passed through a first dispensing device <NUM>. A first moving nozzle <NUM> is positioned over the first set of optical fibers <NUM>-<NUM>. Matrix material <NUM> is applied from the first dispensing nozzle <NUM> on the intersecting junctions between the optical fibers. The matrix material <NUM> fills the gap between the adjacent optical fibers and after curing forms first bonding regions <NUM>.

According to the invention, the matrix material <NUM> comprises a UV curable acrylate material. In comparative examples outside the subject-matter of the claims, the matrix material <NUM> may comprise a resin, other polymeric materials, thermoplastic materials.

The first moving nozzle <NUM> may be oscillating (or may be stationary when dispensing a bead of material between two flexible ribbons) in a direction transverse to the direction of the longitudinal passing fibers or ribbons. In other words, the first moving nozzle <NUM> may be oscillating along the longitudinal direction D2 in <FIG> or into the plane in <FIG>.

Alternately, the matrix material <NUM> is dispensed for a short time before the first moving nozzle <NUM> within the first dispensing device <NUM> shuts it off. For example, the matrix material <NUM> is released while the first set of optical fibers <NUM>-<NUM> moves along a longitudinal direction, which is out of the plane of the page in <FIG>. Subsequently, the first moving nozzle <NUM> is shut off so that the matrix material <NUM> is not released.

The first moving nozzle <NUM> is then moved relative to the first moving carrier <NUM> along a direction D2, transverse to the longitudinal direction along the optical fibers, to move to the next intersecting junction of the first set of optical fibers <NUM>-<NUM>. Further, translation of the first set of optical fibers <NUM>-<NUM> may continue while the first moving nozzle <NUM> is closed. Subsequently, the first moving nozzle <NUM> is opened again and the matrix material <NUM> is released at the intersecting junction between adjacent optical fibers while moving the first set of optical fibers <NUM>-<NUM> along the longitudinal direction. The first moving nozzle <NUM> may thus step through the first set of optical fibers <NUM>-<NUM> until the matrix material <NUM> for forming the predetermined pattern of the first bonding regions <NUM> has been released.

The matrix material <NUM> is then cured to form the first flexible ribbon 50comprising the first bonding regions <NUM> having the first pattern <NUM>, for example. The curing process may comprise passing through a first curing station <NUM>, a room temperature cure for a predetermined time, higher temperature cure (e.g., <NUM> to <NUM>), exposure to UV-light, and others.

The first dispensing device <NUM> may be configured to apply the matrix material <NUM> on to the second set of optical fibers <NUM>-<NUM> after forming the first flexible ribbon <NUM>. For example, the first flexible ribbon <NUM> may be removed from the first moving carrier <NUM> by a pickup reel and the second set of optical fibers <NUM>-<NUM> arranged on the first moving carrier <NUM>. The steps of releasing the matrix material <NUM> may be repeated as described above while forming the first flexible ribbon <NUM> (see also schematic arrows showing the same).

Accordingly, a plurality of flexible ribbons such as the first flexible ribbon <NUM> (as well as subsequently the second flexible ribbon <NUM>) is formed.

<FIG> illustrate the unitized flexible ribbon during formation in accordance with embodiments of the present application. <FIG> (similar to <FIG>) illustrates the formation of a flexible ribbon assembly from a plurality of flexible ribbons in accordance with embodiments of the present invention. <FIG> illustrates a cross-sectional view of the plurality of flexible ribbons during formation of second bonding regions at an opposite bottom side, and <FIG> illustrates a top view of the plurality of flexible ribbons during formation of second bonding regions at the bottom side along a predetermined pattern.

The plurality of flexible ribbons that are designed to be part of the unitized flexible ribbon such as the first flexible ribbon <NUM> and the second flexible ribbon <NUM> are paid off from reels, into a second die <NUM>, and optionally arranged on a second moving carrier <NUM>. In particular, the first flexible ribbon <NUM> and the second flexible ribbon <NUM> are arranged so that a second side <NUM> that is opposite the first side <NUM> comprising the first bonding regions <NUM> faces away from the second moving carrier <NUM>. Alternately, the first flexible ribbon <NUM> and the second flexible ribbon <NUM> may be freely suspended between rollers, which may also provide translational motion along the length of the flexible ribbons (direction of arrow).

The second dispensing device <NUM> may be the same tool as the first dispensing device <NUM> used previously in one or more embodiments. Alternately, the second dispensing device <NUM> to form the unitized ribbon may be different than the first dispensing device <NUM>. Similarly, the second moving carrier <NUM> may be the same or different from the first moving carrier <NUM> in various embodiments. In an example outside the subject-matter of the claims, the matrix material <NUM> dispensed from the first dispensing device <NUM> may be different from the matrix material <NUM> disposed from the second dispensing device <NUM>.

In embodiments such as the one described using <FIG>, <FIG>, or <FIG>, a continuous flow of the matrix material <NUM> from the second dispensing device <NUM> is maintained as the second moving carrier <NUM> moves along a longitudinal direction parallel to the length of the first and the second flexible ribbons <NUM> and <NUM>.

Even, in other embodiments that use intermittent bonding regions such as the illustration of <FIG>, the matrix material <NUM> may still be dispensed continuously. For example, in one illustration, a continuous sinusoidal thread of matrix material <NUM> is applied on the surface of the first flexible ribbon <NUM> and/or the second flexible ribbon <NUM>. By selecting proper viscosity and surface tension, the bonding material forms discrete bonds between successive optical fibers even though applied continuously. Advantageously, continuous application of the matrix material <NUM> to form discrete or intermittent bonding regions is less complicated and therefore less expensive.

However, in other embodiments that use intermittent bonding regions such as the illustration of <FIG>, the matrix material <NUM> is dispensed for a short time before a second moving nozzle <NUM> within the second dispensing device <NUM> shuts it off. For example, the matrix material <NUM> is released while the second moving carrier <NUM> moves along a longitudinal parallel to the length of the optical fibers, which is out of the plane of the page in <FIG>. Subsequently, the second moving nozzle <NUM> is shut off so that the matrix material <NUM> is not applied. The second moving nozzle <NUM> is moved relative to the second moving carrier <NUM> along the transverse direction D2 to move to the next intersecting junction of the optical fibers. Further, another translation of the second moving carrier <NUM> along the longitudinal direction may also be performed while the nozzle is closed. Subsequently, after the translation of the second moving carrier <NUM> in the longitudinal direction and the translation of the second moving nozzle <NUM> in the transverse direction D2, the second moving nozzle <NUM> is opened again and the matrix material <NUM> is released at the intersecting junction between adjacent optical fibers while moving the second moving carrier <NUM> along the longitudinal direction. The second moving nozzle <NUM> may thus step through the first flexible ribbon <NUM> and the second flexible ribbon <NUM> until the matrix material <NUM> for forming the predetermined pattern of the second bonding regions <NUM> has been released. All the translations may be performed simultaneously or concurrently.

As previously described, the matrix material <NUM> is then cured, for example, in a second curing station <NUM> to form the flexible ribbon assembly <NUM>. The flexible ribbon assembly <NUM> is then picked up from the second moving carrier <NUM> by a pick-up reel <NUM>.

In accordance with the embodiments described previously, the second bonding regions <NUM> may be continuous or intermittent and may comprise different patterns, e.g., wavelike or linear pattern with a variety of regular or irregular wavelengths, amplitudes, and phases which may be controlled by the relative positions of the second moving nozzle <NUM> and second moving carrier <NUM> during the application process.

In accordance with the embodiments described previously in <FIG>, the fabrication process is performed with a moving ribbon or ribbon assembly that is passed through a first dispensing device with a nozzle moving in a direction transverse to the direction of the longitudinal passing ribbons. In other embodiments, the fabrication of the unitized flexible ribbon is performed with a stationary ribbon or ribbon assembly and a dispenser traveling over the length of the ribbon. <FIG> and <FIG> illustrate a unitized flexible ribbon during various stages of fabrication in accordance with embodiments of the present application with a stationary ribbon or ribbon assembly.

<FIG> illustrates a plurality of flexible ribbons during formation of first bonding regions at a top side.

Similar to the prior embodiment, matrix material <NUM> is applied from a first dispensing tool <NUM> on the intersecting junctions between the optical fibers. The first dispensing tool <NUM> may be similar to the first dispensing device <NUM> described before. Unlike the prior embodiment, the optical fibers are positioned in a stationary position while the nozzle is moved.

The matrix material <NUM> is dispensed for a short time before a nozzle <NUM> within the first dispensing tool <NUM> shuts it off. For example, the matrix material <NUM> is released while the first dispensing tool <NUM> is moved relative to the first carrier <NUM> along a first direction parallel to the length of the optical fibers, which is into the plane of the page in <FIG>. Subsequently, the matrix material <NUM> is shut off so that the matrix material <NUM> is not released.

The first dispensing tool <NUM> is then moved relative to the first carrier <NUM> along the transverse direction D2 to move to the next intersecting junction of the first set of optical fibers <NUM>-<NUM>. Further, another translation along the first direction may also be performed while the nozzle <NUM> is closed. Subsequently, after the translations in the first and the second directions, the nozzle is opened again and the matrix material <NUM> is released at the intersecting junction between adjacent optical fibers while moving the first dispensing tool <NUM> relative to the first carrier <NUM> along the first direction. The first dispensing tool <NUM> may thus step through the first set of optical fibers <NUM>-<NUM> until the matrix material <NUM> for forming the predetermined pattern of the first bonding regions <NUM> has been released.

The matrix material <NUM> is then cured to form the first flexible ribbon <NUM>. Once the first dispensing tool <NUM> has traversed through all the optical fibers of the first set of optical fibers <NUM>-<NUM>, a curing process may be provided to form the first bonding regions <NUM> having the first pattern <NUM>, for example, as described above. Similarly, the steps of releasing the matrix material <NUM> may be repeated as described above while forming the first flexible ribbon <NUM> (see also schematic arrows showing the same) to form the second flexible ribbon.

Accordingly, a plurality of ribbons such as the first flexible ribbon <NUM> (as well as the second flexible ribbon <NUM>) is formed.

<FIG> illustrates a cross-sectional view of the plurality of flexible ribbons during formation of second bonding regions at an opposite bottom side.

Unlike the prior embodiment of <FIG>, the flexible ribbons are positioned in a stationary position while the dispensing nozzle is moved. Accordingly, the plurality of flexible ribbons that are designed to be part of the unitized flexible ribbon such as the first flexible ribbon <NUM> and the second flexible ribbon <NUM> are arranged on a second carrier <NUM> or held in a stationary position between rollers. In particular, the first flexible ribbon <NUM> and the second flexible ribbon <NUM> are arranged so that a second side <NUM> that is opposite the first side <NUM> comprising the first bonding regions <NUM> faces away from the second carrier <NUM>.

The second dispensing tool <NUM>, which may be similar to the second dispensing device <NUM>, may be the same tool as the first dispensing tool <NUM> used previously in one or more embodiments. Alternately, the second dispensing tool <NUM> to form the unitized ribbon may be different than the first dispensing tool <NUM>. Similarly, the second carrier <NUM> may be the same or different from the first carrier <NUM> in various embodiments. In an example outside the subject-matter of the claims, the matrix material <NUM> dispensed from the first dispensing tool <NUM> may be different from the matrix material <NUM> disposed from the second dispensing tool <NUM>.

In embodiments such as the one described using <FIG>, <FIG>, or <FIG>, a continuous flow of the matrix material <NUM> is maintained as the second dispensing tool <NUM> is moved relative to the second carrier <NUM> along a first direction parallel to the length of the first and the second flexible ribbons <NUM> and <NUM>.

However, in other embodiments that use intermittent bonding regions such as the illustration of <FIG>, the matrix material <NUM> is dispensed for a short time before a nozzle <NUM> within the second dispensing tool <NUM> shuts it off. For example, the matrix material <NUM> is released while the second dispensing tool <NUM> is moved relative to the second carrier <NUM> along a first direction D1 parallel to the length of the optical fibers, which is into the plane of the page in <FIG>. Subsequently, the nozzle235 is shut off so that the matrix material <NUM> is not applied. The second dispensing tool <NUM> is moved relative to the second carrier <NUM> along the second direction D2 to move to the next intersecting junction of the optical fibers. Further, another translation along the first direction D1 may also be performed while the nozzle is closed. Subsequently, after the translations in the first and the second directions, the nozzle is opened again and the matrix material <NUM> is released at the intersecting junction between adjacent optical fibers while moving the second dispensing tool <NUM> relative to the second carrier <NUM> along the first direction. The second dispensing tool <NUM> may thus step through the first flexible ribbon <NUM> and the second flexible ribbon <NUM> until the matrix material <NUM> for forming the predetermined pattern of the second bonding regions <NUM> has been released.

The matrix material <NUM> is then cured, for example, as described previously to form the flexible ribbon assembly <NUM>.

In accordance with the embodiments described previously, the second bonding regions <NUM> may be continuous or intermittent and may comprise different patterns, e.g., wavelike or linear pattern with a variety of regular or irregular wavelengths, amplitudes, and phases which may be controlled by the relative positions of the second dispensing tool <NUM> and second carrier <NUM> during the application process.

Claim 1:
An optical fiber cable comprising:
a flexible ribbon assembly (<NUM>) comprising a plurality of flexible ribbons (<NUM>,<NUM>), each of the plurality of flexible ribbons comprising a plurality of optical fibers (<NUM>-<NUM>, <NUM>-<NUM>);
a plurality of first bonding regions (<NUM>), wherein adjacent ones of the plurality of optical fibers are attached to each other by one of the plurality of first bonding regions; and
a second bonding region (<NUM>) joining a first one of the plurality of flexible ribbons with a second one of the plurality of flexible ribbons, wherein the plurality of first bonding regions is disposed at a first side (<NUM>) of the plurality of flexible ribbons, as seen from a top view of the unitized flexible ribbon assembly, wherein the second bonding region is disposed at a second side (<NUM>) of the plurality of flexible ribbons, as seen from a bottom view of the unitized flexible ribbon assembly, and wherein the second side is opposite to the first side, wherein the plurality of first bonding regions have a first pattern (<NUM>-<NUM>), said first pattern (<NUM>-<NUM>) comprising a wave pattern,
wherein both the plurality of first bonding regions and the second bonding region comprise a UV cured acrylate material,
wherein the second bonding region has a lower bonding strength than one of the plurality of first bonding regions.