Patent Description:
The present application claims priority from <CIT>.

<CIT>discloses an optical fiber ribbon in which an optical fiber tape resin is divided by a divided portion provided intermittently along a longitudinal direction of the optical fiber ribbon, and the optical fiber tape resin remains in a non-divided portion in a state where the optical fiber tape resin is continuous in the longitudinal direction.

<CIT>discloses an optical fiber ribbon in which three-core or more optical fibers are arranged in parallel. In the optical fiber ribbon, two adjacent optical fibers are connected by a connected section, and the connected section is intermittently provided in each of a longitudinal direction of the optical fiber ribbon and a width direction of the optical fiber ribbon. Further, <CIT>discloses that an outer diameter of an optical fiber constituting the optical fiber ribbon is <NUM> or less, and a distance between centers of adjacent optical fibers is <NUM> ± <NUM>.

Other examples of the prior art can be found in documents <CIT>, <CIT>, <CIT>, and <CIT>.

An intermittent connection-type optical fiber ribbon according to the invention is defined by the technical features of claim <NUM>.

An optical fiber cable according to an aspect of the present disclosure includes the technical features of claim <NUM>.

A connector-equipped optical fiber cord according to an aspect of the present disclosure includes the technical features of claim <NUM>.

When discussing an increase in a density of optical fibers in an optical fiber cable, it is considered to mount an intermittent connection-type optical fiber ribbon using optical fibers having a diameter smaller than <NUM> in the related art.

When the intermittent connection-type optical fiber ribbon in the related art such as the optical fiber ribbons disclosed in <CIT>and <CIT> uses thin optical fibers as described above and is formed with a divided portion and an intermittent pattern portion (connected section and non-connected section), rigidity of the optical fiber ribbon is likely to be low and the optical fiber ribbon is likely to be deflected. It is difficult to set the intermittent connection-type optical fiber ribbon at an accurate fusion position using a fiber holder when the intermittent connection-type optical fiber ribbon is collectively fusion-spliced. When the fused intermittent connection-type optical fiber ribbon is conveyed to a protective sleeve heating unit, optical fibers are likely to be deflected and local bending is likely to occur in the fused intermittent connection-type optical fiber ribbon. On the other hand, when rigidity of the intermittent connection-type optical fiber ribbon is too high, it is difficult to deform the intermittent connection-type optical fiber ribbon. Therefore, when a bending pressure is applied, the intermittent connection-type optical fiber ribbon cannot absorb the bending pressure. Therefore, when the optical fiber ribbon is mounted in an optical fiber cable at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is likely to occur.

An object of the present disclosure is to provide an intermittent connection-type optical fiber ribbon, an optical fiber cable, and a connector-equipped optical fiber cord, in which even when optical fibers having a small diameter are used, the optical fibers are less likely to be deflected when the optical fibers are collectively fusion-spliced, and a macro bending loss is less likely to occur even when a density is increased.

Even when the intermittent connection-type optical fiber ribbon as defined by claim <NUM> uses small-diameter optical fibers having an outer diameter of <NUM> or more and <NUM> or less, a catenary amount of a tip that is held is <NUM> or more and <NUM> or less. That is, since the catenary amount is <NUM> or less, the rigidity is appropriately large, and optical fibers set in a fiber holder are less likely to be deflected. Therefore, positions of tips of the optical fibers are less likely to be misaligned when the optical fibers are collectively fusion-spliced. In addition, when the fused intermittent connection-type optical fiber ribbon is conveyed to a protective sleeve heating unit, local bending is less likely to occur. On the other hand, since the catenary amount is <NUM> or more, the intermittent connection-type optical fiber ribbon does not have too large rigidity, can be appropriately deformed against a bending pressure, and can absorb the bending pressure. Therefore, when the intermittent connection-type optical fiber ribbon is mounted in an optical fiber cable at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is less likely to occur.

(<NUM>) In the intermittent connection-type optical fiber ribbon,
the number of the plurality of optical fibers may be <NUM>, and a width in an arrangement direction of the plurality of optical fibers may be <NUM> or less.

According to this configuration, even when the number of optical fibers is <NUM>, the width of the intermittent connection-type optical fiber ribbon in the arrangement direction is <NUM> or less. Therefore, the intermittent connection-type optical fiber ribbon can be collectively fusion-spliced using an existing fusion splicer that collectively fusion-spliced a <NUM>-core optical fiber ribbon.

(<NUM>) A distance between centers of the adjacent optical fibers may be <NUM> ± <NUM>.

According to this configuration, since the distance between the centers of adjacent optical fibers is <NUM> ± <NUM>, the width of the intermittent connection-type optical fiber ribbon in the arrangement direction can be reduced.

(<NUM>) The number of the plurality of optical fibers may be
a multiple of <NUM>, and may be <NUM> or more.

According to this configuration, since the number of optical fibers is a multiple of <NUM>, a bidirectional transmission is easily performed for every four cores. In addition, since the number of the optical fibers is <NUM> or more, rigidity of the intermittent connection-type optical fiber ribbon is easy to be increased.

(<NUM>) The plurality of optical fibers may have
a bending loss of <NUM> dB/<NUM> turns or less when a bending radius R is <NUM>.

According to this configuration, since the optical fibers have a bending loss of <NUM> dB/<NUM> turns or less when the bending radius R is <NUM>, the bending loss can be reduced.

Since the Young's modulus of the secondary resin at <NUM> is <NUM> MPa or more, the coating layers on an outer side of the optical fiber have appropriate hardness. Therefore, a micro bending loss that occurs when an uneven lateral pressure is applied to the optical fiber is less likely to occur. Therefore, a lateral pressure property of the intermittent connection-type optical fiber ribbon is improved.

(<NUM>) In the intermittent connection-type optical fiber ribbon.

According to this configuration, the tape resin of the connected section between the optical fibers where the non-connected section is formed can be easily ripped starting from the boundary where the end portion of the slit is formed by cutting the end portion into an acute angle. Since the non-connected section is formed for every four cores, the intermittent connection-type optical fiber ribbon can be easily divided for every four or a number of a multiple of four cores.

An optical fiber cable according to the present invention as defined by claim <NUM> has a core density <NUM> core/mm<NUM> or more.

According to this configuration, since the optical fiber cable has a core density of <NUM> core/mm<NUM> or more, optical fibers can be mounted at a high density. Rigidity of the intermittent connection-type optical fiber ribbon mounted in the optical fiber cable is appropriately large. Therefore, positions of tips of the optical fibers are less likely to be misaligned when the intermittent connection-type optical fiber ribbon taken out from the optical fiber cable in which the optical fibers are mounted at a high density is collectively fusion-spliced. Further, local bending is less likely to occur in the fused intermittent connection-type optical fiber ribbon taken out from the optical fiber cable in the manner described above when the fused intermittent connection-type optical fiber ribbon is conveyed to a protective sleeve heating unit.

Further, the intermittent connection-type optical fiber ribbon does not have too large rigidity, can be appropriately deformed against a bending pressure, and can absorb the bending pressure. Therefore, when the intermittent connection-type optical fiber ribbon is mounted in the optical fiber cable at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is less likely to occur.

A connector-equipped optical fiber cord as defined by claim <NUM> includes an optical fiber cord including the intermittent connection-type optical fiber ribbon and a connector connected to the optical fiber cord.

According to this configuration, since the intermittent connection-type optical fiber ribbon provided in the optical fiber cord has appropriately large rigidity, when the optical fibers are disassembled from one another and are set in a connector during manufacturing the connector-equipped optical fiber cord, the optical fibers are less likely to be deflected. Therefore, the optical fibers in the connector can be easily set in a desired arrangement and at a desired arrangement pitch, and thus it is possible to provide a connector-equipped optical fiber cord that is easily manufactured.

Further, the intermittent connection-type optical fiber ribbon does not have too large rigidity, can be appropriately deformed against a bending pressure, and can absorb the bending pressure. Therefore, even when the optical fibers are mounted in the optical fiber cord at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is less likely to occur.

According to the present disclosure, it is possible to provide an intermittent connection-type optical fiber ribbon, an optical fiber cable, and a connector-equipped optical fiber cord, in which even when optical fibers having a small diameter are used, the optical fibers are less likely to be deflected when the optical fibers are collectively fusion-spliced, and a macro bending loss is less likely to occur even when a density is increased.

Specific examples of an intermittent connection-type optical fiber ribbon, an optical fiber cable, and a connector-equipped optical fiber cord according to an embodiment of the present disclosure will be described below with reference to the drawings.

The present disclosure is not limited to these examples, and is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

<FIG> are views showing an example of an optical fiber ribbon. As shown in <FIG>, in an optical fiber ribbon <NUM> in the present example, a plurality of (the number of the optical fiber ribbons is <NUM> in the present example) of the optical fibers <NUM> (11A to 11P in the present example) are arranged in parallel in a direction orthogonal to a longitudinal direction of the optical fibers <NUM>. The <NUM> optical fibers 11A to 11P are connected by a resin in a manner in which adjacent optical fibers are at least partially brought into contact with each other.

The optical fiber ribbon <NUM> is an intermittent connection-type optical fiber ribbon in which, for every two optical fibers, a connected section <NUM> in a state where optical fibers are connected by a resin and a non-connected section <NUM> in a state where optical fibers are not connected by a resin are intermittently provided in the longitudinal direction for a part of or all of the plurality of optical fibers <NUM>. In the optical fiber ribbon <NUM>, the connected section <NUM> and the non-connected section <NUM> are provided between the optical fibers 11B and 11C, between the optical fibers 11D and 11E, between the optical fibers 11F and <NUM>, between the optical fibers <NUM> and 11I, between the optical fibers 11J and <NUM>, between the optical fibers <NUM> and <NUM>, and between the optical fibers 11N and 11O.

<FIG> shows the optical fiber ribbon <NUM> in a state where the non-connected section <NUM> is expanded in an arrangement direction of the optical fibers 11A to 11P. <FIG> is a cross-sectional view taken along a line A-A of the optical fiber ribbon <NUM> in <FIG>. <FIG> is a cross-sectional view taken along the line A-A of the optical fiber ribbon <NUM> in a state where the non-connected section <NUM> is not expanded.

Although the intermittent connection-type optical fiber ribbon includes <NUM> optical fibers in the present example, the number of the optical fibers is not limited to <NUM>. The number of the optical fibers may be <NUM> or more, and may be a multiple of <NUM>. The number of the optical fibers may be <NUM>, <NUM>. <NUM>, and the like.

As shown in <FIG> and <FIG>, each of the optical fibers <NUM> includes, for example, a glass fiber <NUM> including a core and a cladding, and a two-layer coating layer that covers a periphery of the glass fiber <NUM>. An inner coating layer of the two-layer coating layer is formed of a primary resin <NUM>. An outer coating layer of the two-layer coating layer is formed of a secondary resin <NUM>. A colored layer or the like may be provided on an outer side of the two-layer coating layer.

A soft resin having a relatively low Young's modulus is used as a buffer layer in the primary resin <NUM> that is in contact with the glass fiber <NUM>. A hard resin having a relatively high Young's modulus is used as a protective layer in the secondary resin <NUM>. The Young's modulus at <NUM> of the secondary resin <NUM> is <NUM> MPa or more, preferably <NUM> MPa or more, and more preferably <NUM> MPa or more.

The primary resin <NUM> and the secondary resin <NUM> are formed of an ultraviolet curable resin, a thermosetting resin, and the like. The optical fiber <NUM> has a bending loss of <NUM> dB/<NUM> turns or less when a bending radius R is <NUM>. In order to increase lateral pressure resistance, a bending reinforced fiber specified in ITU-TG. A/B may be used as the optical fiber <NUM>.

A tape resin <NUM> that connects the optical fibers 11A to 11P is provided around the optical fiber <NUM>. The optical fibers 11A to 11P are arranged in parallel in a state where the optical fibers 11A to 11P are in contact with one another, and are connected by being collectively coated with the tape resin <NUM>. The tape resin <NUM> that collectively coats the optical fibers 11A to 11P are provided in a manner of forming a shape having recessed portions 17a between the optical fibers corresponding to a depression formed between adjacent optical fibers. As described above, for every two optical fibers, the connected section <NUM> and the non-connected section <NUM> are intermittently provided in the tape resin <NUM> in the longitudinal direction. In this manner, every two optical fibers of the optical fiber ribbon <NUM> are intermittently connected by the tape resin <NUM> in the longitudinal direction of the optical fiber ribbon <NUM>.

As shown in <FIG>, the non-connected section <NUM> of the optical fiber ribbon <NUM> is formed such that an end portion of a slit 13a passing through an upper surface and a lower surface of the optical fiber ribbon <NUM> relative to the tape resin <NUM> is cut into an acute angle relative to a boundary 13b between the non-connected section <NUM> and the connected section <NUM>. The slit 13a is formed by cleaving the tape resin <NUM> in the recessed portion 17a provided between optical fibers.

An outer diameter B (see <FIG>) of each of the optical fibers 11A to 11P is <NUM> or more and <NUM> or less. A distance C between centers of adjacent optical fibers among the optical fibers 11A to 11P is <NUM> or more and <NUM> or less. A thickness D of the optical fiber ribbon <NUM> is <NUM> or less. A width E of the optical fiber ribbon <NUM> (a width in an arrangement direction of the optical fibers) is <NUM> or less when the number of the optical fibers is <NUM>.

Although the optical fiber ribbon <NUM> in the present example has a configuration in which the optical fibers 11A to 11P are arranged in parallel in a state where the optical fibers 11A to 11P are brought into contact with one another and a periphery of the optical fibers 11A to 11P is coated with the tape resin <NUM>, the present invention is not limited to such a configuration. For example, the optical fibers 11A to 11P may be arranged in parallel in a state where a small gap is present between adjacent optical fibers, and the optical fibers 11A to 11P may be coated with the tape resin <NUM> in a state where the tape resin <NUM> enters the gap between adjacent optical fibers.

<FIG> is a view showing another example of an optical fiber ribbon according to the present embodiment. As shown in <FIG>, an optical fiber ribbon <NUM> in the present example is different from the optical fiber ribbon <NUM> in <FIG> in which the connected section <NUM> and the non-connected section <NUM> are provided for every two optical fibers, in that a connected section <NUM> and a non-connected section <NUM> are provided between optical fibers. Similar to the non-connected section <NUM> of the optical fiber ribbon <NUM> in <FIG>, the non-connected section <NUM> is formed such that an end portion of a slit 23a is cut into an acute angle relative to a boundary 23b between the connected section <NUM> and the non-connected section <NUM>.

The optical fiber ribbon <NUM> includes <NUM> optical fibers <NUM> (21A to 21P in the present example), and the number of the optical fibers is the same as that of the optical fiber ribbon <NUM> in <FIG>. Other configurations, for example, a glass fiber and a coating layer constituting each optical fiber, an outer diameter B of the optical fiber, a distance C between centers of adjacent optical fibers, a bending loss of the optical fibers, a thickness D and a width E of the optical fiber ribbon, and the like are the same as those of the optical fiber ribbon <NUM> in <FIG>.

<FIG> is a view showing another example of an optical fiber ribbon according to the present embodiment. As shown in <FIG>, an optical fiber ribbon <NUM> in the present example is different from the optical fiber ribbon <NUM> in <FIG> in which the connected section <NUM> and the non-connected section <NUM> are provided for every two optical fibers, in that a connected section <NUM> and a non-connected section <NUM> are provided for every four optical fibers. Similar to the non-connected section <NUM> of the optical fiber ribbon <NUM> in <FIG>, the non-connected section <NUM> is formed such that an end portion of a slit 33a is cut into an acute angle relative to a boundary 33b between the connected section <NUM> and the non-connected section <NUM>.

The optical fiber ribbon <NUM> has <NUM> optical fibers <NUM> (31A to 31P in the present example), and the number of the optical fibers is the same as that of the optical fiber ribbon <NUM> in <FIG>. Similar to the optical fiber ribbon <NUM> shown in <FIG>, other configurations are the same as those of the optical fiber ribbon <NUM> shown in <FIG>.

<FIG> is a view showing catenary amounts of the optical fiber ribbons <NUM>, <NUM>, and <NUM> described above. As shown in <FIG>, appropriate rigidity of each of the optical fiber ribbons is specified based on a deflection amount (catenary amount) of the optical fiber ribbon <NUM> (<NUM>, <NUM>) when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is set in a fiber holder <NUM> for fusion and an axial misalignment error of optical fibers at the time of fusion in the present example.

Specifically, the fiber holder <NUM> holds the optical fiber ribbon <NUM> (<NUM>, <NUM>) in a horizontal direction from a position of a length G of <NUM> with reference to a tip F to a predetermined position (for example, a position of <NUM> from the tip F). In the present example, a catenary amount H of the tip F of the cantilevered optical fiber ribbon <NUM> (<NUM>, <NUM>) having a length G of <NUM> that protrudes from a portion that is held is measured. The tip F refers to a tip portion when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is cut along a direction orthogonal to the longitudinal direction of the optical fiber ribbon <NUM> (<NUM>, <NUM>). When the catenary amount H is large, the tip of the optical fiber ribbon <NUM> (<NUM>, <NUM>) spread in a width direction for each fiber at the time of fusion, and an axial misalignment between the optical fiber ribbons to be fused occurs. As a result, work efficiency is lowered. Therefore, in the present example, in order to prevent the axial misalignment of the optical fiber ribbons at the time of fusion, rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is specified so that the catenary amount H of the tip F of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is <NUM> or less.

<FIG> is a view showing a positional relationship between a fusion splicer <NUM> and the optical fiber ribbon <NUM> (<NUM>, <NUM>) set in the fiber holder <NUM> at the time of fusing the optical fiber ribbon <NUM> (<NUM>, <NUM>). As shown in <FIG>, the fusion splicer <NUM> is provided with a V groove <NUM> in which the optical fibers <NUM> (<NUM>, <NUM>) of the optical fiber ribbon <NUM> (<NUM>, <NUM>) are accommodated, and a discharge unit <NUM> including a pair of electrodes for discharging. For example, a distance I from a side end portion of the fusion splicer <NUM> to a central position of the discharge unit <NUM> is <NUM>.

The optical fiber ribbon <NUM> (<NUM>, <NUM>) set in the fiber holder <NUM> at the time of fusion is, for example, in a state where the optical fiber ribbon <NUM> (<NUM>, <NUM>) includes the tape resin <NUM> from a tip of the fiber holder <NUM> to a portion having a length J of <NUM> to the tip in a portion protruding from the tip of the fiber holder <NUM>. A portion from the portion having the length J to a portion having a length K of <NUM> toward the tip of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is in a state where the tape resin <NUM> is peeled off from the optical fibers <NUM> (<NUM>, <NUM>). A portion having a length L of <NUM> to <NUM> from the tip of the optical fiber <NUM> (<NUM>, <NUM>) is in a state where the primary resin <NUM> and the secondary resin <NUM> are peeled off from the glass fiber <NUM>. Then, two optical fiber ribbons respectively set on two fiber holders <NUM> are arranged relative to the fusion splicer <NUM> such that tips of the glass fibers <NUM> abut each other between the pair of electrodes of the discharge unit <NUM>. At this time, the portion of the optical fiber <NUM> (<NUM>, <NUM>) from which the tape resin <NUM> is peeled off is accommodated in each V groove <NUM> of the fusion splicer <NUM>. For example, arc discharge is performed from the pair of electrodes of the discharge unit <NUM>, and the two optical fiber ribbons <NUM> (<NUM>, <NUM>) are fused to each other.

On the other hand, in the measurement in <FIG>, when the catenary amount H of the tip F of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is small, the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is large. In a case where the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is too large, when a bending pressure is applied to the optical fiber ribbon <NUM> (<NUM>, <NUM>), the optical fiber ribbon <NUM> (<NUM>, <NUM>) cannot absorb the bending pressure. When the optical fiber ribbon <NUM> (<NUM>, <NUM>) is mounted in an optical fiber cable at a high density, a macro bending loss is likely to occur. Therefore, in order to prevent the occurrence of the macro bending loss when a bending pressure is applied, the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is specified such that the catenary amount H of the tip F of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is <NUM> or more in the present example.

In the optical fiber ribbon <NUM> (<NUM>, <NUM>), an outer diameter of the optical fiber <NUM> (<NUM>, <NUM>) is <NUM> or more and <NUM> or less. The optical fiber ribbon <NUM> (<NUM>, <NUM>) is configured such that when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is held in the horizontal direction from a position of <NUM> with reference to the tip of the optical fiber ribbon <NUM> (<NUM>, <NUM>) to a predetermined position, the catenary amount of the tip is <NUM> or more and <NUM> or less. Since the catenary amount of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is <NUM> or less, the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is appropriately large. Even when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is set in the fiber holder <NUM> at the time of fusion, the optical fiber <NUM> (<NUM>, <NUM>) is less likely to be deflected. Therefore, when fusion-splicing is collectively performed, the tip of the optical fiber ribbon <NUM> (<NUM>, <NUM>) does not spread in the width direction for each fiber, an axial misalignment between the optical fiber ribbons to be fused is less likely to occur. When the fused optical fiber ribbon <NUM> (<NUM>, <NUM>) is conveyed to, for example, a protective sleeve heating unit that is a subsequent manufacturing process, local bending of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is less likely to occur. Therefore, it is possible to efficiently perform a connection work of the optical fiber ribbon <NUM> (<NUM>, <NUM>) in the present example.

Since the optical fiber ribbon <NUM> (<NUM>, <NUM>) has the catenary amount of <NUM> or more, the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is not too large. Therefore, the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be appropriately deformed against a bending pressure and can absorb the bending pressure. Therefore, when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is mounted in an optical fiber cable at a high density, a macro bending loss due to an extremely small bending radius is less likely to occur.

In the optical fiber ribbon <NUM> (<NUM>, <NUM>), the Young's modulus at, for example, <NUM> of the secondary resin <NUM> that forms a coating layer outside the optical fiber <NUM> (<NUM>, <NUM>) is <NUM> MPa or more. Since the secondary resin <NUM> has appropriate hardness, a micro bending loss is less likely to occur even when an uneven lateral pressure is applied to the optical fiber <NUM> (<NUM>, <NUM>). Therefore, a lateral pressure property of the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be improved in the present example.

The optical fiber ribbon <NUM> (<NUM>, <NUM>) is configured such that the number of optical fibers is <NUM>, and a width in the arrangement direction of the optical fibers is <NUM> or less. The width is equal to a width of a <NUM>-core optical fiber ribbon in the related art in which an outer diameter of the optical fiber is <NUM>. As a result, even the number of the optical fibers is <NUM> in the optical fiber ribbon <NUM> (<NUM>, <NUM>) in the present example, the optical fibers can be collectively fusion-spliced using a fusion-splicer that collectively fusion-spliced the <NUM>-core optical fiber ribbon in the related art.

The optical fiber ribbon <NUM> (<NUM>, <NUM>) is configured such that the distance C between the centers of adjacent optical fibers <NUM> (<NUM>, <NUM>) is <NUM> ± <NUM>. Therefore, a width in an arrangement direction of the optical fibers <NUM> (<NUM>, <NUM>) of the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be reduced in the present example.

For the <NUM>-core optical fiber ribbon in the related art, when a bidirectional transmission is performed for every four fibers, eight fibers are used and the remaining four fibers are not used among the <NUM> fibers. In contrast, since the optical fiber ribbon <NUM> (<NUM>, <NUM>) has optical fibers whose number is a multiple of <NUM>, it is easy to perform a bidirectional transmission for every four cores using all of the optical fibers <NUM> (<NUM>, <NUM>) in the present example. Even in the case of a multi-core optical fiber ribbon <NUM> (<NUM>, <NUM>) having <NUM> or more cores, the rigidity is not too large, and the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be appropriately deformed against a bending pressure.

Since the optical fiber ribbon <NUM> (<NUM>, <NUM>) is configured such that a bending loss is <NUM> dB/<NUM> turns or less when the bending radius R of the optical fiber is <NUM>, the bending loss of the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be sufficiently reduced in the present example.

In the optical fiber ribbon <NUM> (<NUM>, <NUM>), the non-connected section <NUM> (<NUM>, <NUM>) is formed such that, between adjacent optical fibers, an end portion of the slit 13a (23a, 33a) passing through the upper surface and the lower surface of the optical fiber ribbon <NUM> (<NUM>, <NUM>) relative to the tape resin <NUM> is cut into an acute angle relative to the boundary 13b (23b, 33b) between the connected section <NUM> (<NUM>, <NUM>) and the non-connected section <NUM> (<NUM>, <NUM>).

Accordingly, the tape resin <NUM> of the connected section <NUM> (<NUM>, <NUM>) between optical fibers where the non-connected section <NUM> (<NUM>, <NUM>) is formed can be easily ripped starting from the boundary 13b (23b, 33b) where the end portion of the slit 13a (23a, 33a) is formed by cutting the end portion into an acute angle in the present example.

In the optical fiber ribbon <NUM>, since the non-connected section <NUM> (<NUM>, <NUM>) is formed for every four cores, the optical fiber ribbon <NUM> can be easily divided for every four or a number of a multiple of four cores.

Next, an optical fiber cable according to the present embodiment will be described with reference to <FIG> and <FIG>. <FIG> is a view showing an example of a slotless type optical fiber cable using the optical fiber ribbon <NUM> (<NUM>, <NUM>) according to the present embodiment. <FIG> is a view showing an example of a slot type optical fiber cable using the optical fiber ribbon <NUM> (<NUM>, <NUM>) according to the present embodiment.

A slotless type optical fiber cable <NUM> shown in <FIG> includes a cylindrical tube <NUM> and a plurality of optical fiber ribbons <NUM> (<NUM>, <NUM>) mounted in the tube <NUM>. The optical fiber ribbons <NUM> (<NUM>, <NUM>) are assembled in a manner of being rolled and are stranded together. In addition, a plurality of fillers (tensile strength fibers or the like) are accommodated in the tube <NUM> so as to fill gaps among the optical fiber ribbons <NUM> (<NUM>, <NUM>). An outer sheath <NUM> covers a periphery of the tube <NUM> together with a tension member <NUM>. A rip cord <NUM> is provided inside the outer sheath <NUM>.

In the optical fiber cable <NUM>, a core density of the optical fibers <NUM> (<NUM>, <NUM>) per unit area in a cable cross section is <NUM> core/mm<NUM> or more. The core density is calculated by the number of optical fibers and/or a cross-sectional area of the optical fiber cable. For example, the slotless type optical fiber cable <NUM> shown in <FIG> has <NUM> cores and when the optical fiber cable <NUM> having an outer diameter of <NUM> is manufactured, the optical fibers <NUM> (<NUM>, <NUM>) can be mounted in the optical fiber cable <NUM> at a core density of <NUM> core/mm<NUM>.

A slot type optical fiber cable <NUM> shown in <FIG> includes a slot rod <NUM> having a plurality of slot grooves <NUM>, and a plurality of optical fiber ribbons <NUM> (<NUM>, <NUM>) accommodated in the slot grooves <NUM>. The slot rod <NUM> is provided with a tension member <NUM> at the center of the optical fiber cable <NUM>, and has a structure in which the plurality of slot grooves <NUM> are provided radially. The optical fiber ribbons <NUM> (<NUM>, <NUM>) are assembled in a manner of being rolled, are stranded together, and are accommodated in the slot grooves <NUM>. A press winding tape <NUM> is wound around the slot rod <NUM>, and an outer sheath <NUM> is formed around the press winding tape <NUM>.

A core density of the optical fiber cable <NUM> is <NUM> core/mm<NUM> or more. For example, the slot type optical fiber cable <NUM> shown in <FIG> has <NUM> cores and when the optical fiber cable <NUM> having an outer diameter of <NUM> is manufactured, the optical fibers <NUM> (<NUM>, <NUM>) can be accommodated in the optical fiber cable <NUM> at a core density of <NUM> core/mm<NUM>.

The optical fiber cables <NUM> and <NUM> are configured such that the core density of each of the optical fiber cables is <NUM> core/mm<NUM> or more. Therefore, the optical fibers <NUM> (<NUM>, <NUM>) can be mounted in the optical fiber cables <NUM> and <NUM> at a high density in the present example. In addition, rigidity of the optical fiber ribbons <NUM> (<NUM>, <NUM>) mounted in the optical fiber cables <NUM> and <NUM> is appropriately large in the present example. Therefore, when the optical fiber ribbons <NUM> (<NUM>, <NUM>) are taken out from the optical fiber cables <NUM> and <NUM> in which the optical fibers <NUM> (<NUM>, <NUM>) are mounted at a high density, and the optical fibers <NUM> (<NUM>, <NUM>) are collectively fusion-spliced, the optical fibers <NUM> (<NUM>, <NUM>) are less likely to be deflected, and tips of the optical fibers <NUM> (<NUM>, <NUM>) are less likely to be misaligned. The fused optical fiber ribbons <NUM> (<NUM>, <NUM>) that are taken out from the optical fiber cables <NUM> and <NUM> in a manner described above are less likely to be locally bent when, for example, the optical fiber ribbons <NUM> (<NUM>, <NUM>) are conveyed to a protective sleeve heating unit in a subsequent manufacturing process.

Since the rigidity of the optical fiber ribbons <NUM> (<NUM>, <NUM>) is not too large, the optical fiber ribbons <NUM> (<NUM>, <NUM>) can be appropriately deformed against a bending pressure, and can absorb the bending pressure.

Therefore, when the optical fiber ribbons <NUM> (<NUM>, <NUM>) are mounted in the optical fiber cables <NUM> and <NUM> at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is less likely to occur.

Next, a connector-equipped optical fiber cord according to the present embodiment will be described with reference to <FIG> and <FIG>. <FIG> is a view showing an example of a connector-equipped optical fiber cord using the optical fiber ribbon <NUM> (<NUM>, <NUM>) according to the present embodiment. <FIG> is a front view showing a connector insertion and removal portion of the connector-equipped optical fiber cord shown in <FIG>.

As shown in <FIG>, a connector-equipped optical fiber cord <NUM> includes an optical fiber cord <NUM> in which the optical fiber ribbon <NUM> (<NUM>, <NUM>) is accommodated, and a connector portion <NUM> connected to the optical fiber cord <NUM>. For example, two <NUM>-core optical fiber ribbons or one <NUM>-core optical fiber ribbon is accommodated in the optical fiber cord <NUM>. The connector portion <NUM> is formed of a multi-fiber push-on (MPO) connector that can collectively connect a plurality of optical fibers. As shown in <FIG>, the connector portion <NUM> includes an insertion and removal portion <NUM> to be inserted into or removed from another connector, adapter, or the like. The insertion and removal portion <NUM> is provided with <NUM> (<NUM> × <NUM> rows) through holes <NUM> into which tip portions of the respective optical fibers <NUM> (<NUM>, <NUM>) of the optical fiber ribbon <NUM> (<NUM>, <NUM>) are inserted.

The optical fiber ribbon <NUM> (<NUM>, <NUM>) provided in the connector-equipped optical fiber cord <NUM> has appropriately large rigidity. Therefore, when the optical fibers <NUM> (<NUM>, <NUM>) are disassembled from one another and are set in the connector portion <NUM> during manufacturing the connector-equipped optical fiber cord <NUM>, the optical fibers are less likely to be deflected. Therefore, in the connector-equipped optical fiber cord <NUM>, the optical fibers <NUM> (<NUM>, <NUM>) of the multi-core optical fiber ribbon <NUM> (<NUM>, <NUM>) that has <NUM> or more cores and are accommodated in the connector portion <NUM> can be easily set (wired) in a desired arrangement and at a desired arrangement pitch. Therefore, it is easy to manufacture the connector-equipped optical fiber cord <NUM>.

Since the rigidity of the optical fiber ribbon <NUM> (<NUM>, <NUM>) is not too large, the optical fiber ribbon <NUM> (<NUM>, <NUM>) can be appropriately deformed against a bending pressure, and can absorb the bending pressure. Therefore, when the optical fiber ribbon <NUM> (<NUM>, <NUM>) is mounted in the optical fiber cord <NUM> at a high density, a macro bending loss that is a bending loss due to an extremely small bending radius is less likely to occur.

In the intermittent connection-type optical fiber ribbon according to the present embodiment, connection workability and a high density property were evaluated for a plurality of samples having different catenary amounts H. Evaluation results are shown in a Table <NUM> together with an evaluation for a non-intermittent optical fiber ribbon serving as a comparative example.

In Table <NUM>, all of samples No. <NUM> to <NUM> were <NUM>-core optical fiber ribbons, and a resin having a Young's modulus of <NUM> MPa at <NUM> was used for the secondary resin <NUM> of an optical fiber in each of the optical fiber ribbons. An outer diameter of each optical fiber is <NUM>. The samples No. <NUM> to <NUM> are intermittent connection-type optical fiber ribbons, and the sample No. <NUM> is a non-intermittent optical fiber ribbon serving as a comparative example. In the samples No. <NUM> to No. <NUM>, an intermittent pattern is for every one core, and the intermittent pattern is the same as that of the optical fiber ribbon <NUM>. In the samples No. <NUM> to <NUM>, an intermittent pattern is for every two cores, and the intermittent pattern is the same as that of the optical fiber ribbon <NUM>.

A connected section ratio represents a ratio of a length of the connected section to a length of the non-connected section in the longitudinal direction of the intermittent connection-type optical fiber ribbon. When the connected section ratio is large, a region occupied by the connected section in the intermittent connection-type optical fiber ribbon is large, and the rigidity of the intermittent connection-type optical fiber ribbon is large. Therefore, the intermittent connection-type optical fiber ribbon is less likely to be deflected, and the catenary amount H is small.

On the other hand, when the connected section ratio is small, a region occupied by the connected section in the intermittent connection-type optical fiber ribbon is small, and the rigidity of the intermittent connection-type optical fiber ribbon is small. Therefore, the intermittent connection-type optical fiber ribbon is likely to be deflected, and the catenary amount H is large.

As described above, in the intermittent connection-type optical fiber ribbon, the catenary amount H is changed by changing the connected section ratio.

The connection workability is a relative value obtained by setting a work time of the sample No. <NUM> that is a non-intermittent optical fiber ribbon to <NUM> when the fiber holder <NUM> and the fusion splicer <NUM> shown in <FIG> are used to perform a fusion work of the optical fiber ribbon. When the connection workability exceeded <NUM>, it was determined that the workability was poor, and an evaluation B was given. When the connection workability was <NUM> or less, it was determined that the workability was good, and an evaluation A was given. Furthermore, one having connection workability of <NUM> (equal to that of the non-intermittent connection-type) was determined to be better workability, and an evaluation S was given. That is, samples having the evaluation A or the evaluation S are intermittent connection-type optical fiber ribbons having good connection workability.

The high density property was evaluated by a maximum core density at which the optical fiber ribbons in the samples described above can be mounted in the optical fiber cable <NUM> such that a wavelength of signal light was <NUM> and a bending loss was <NUM> dB/km or less when the optical fiber ribbons in the samples described above were mounted in the optical fiber cable <NUM>. An evaluation criteria was set in which the high density property was determined as good such that when a core density was larger than a core density (<NUM> core/mm<NUM>) of the sample No. <NUM> that is a non-intermittent optical fiber ribbon, an evaluation A was given when a core density was <NUM> core/mm<NUM> or more and <NUM> core/mm<NUM> or less, and an evaluation S was given when a core density exceeded <NUM> core/mm<NUM>. The high density property was determined as poor and an evaluation B was given when a core density was <NUM> core/mm<NUM> or less. That is, samples having the evaluation A or the evaluation S are intermittent connection-type optical fiber ribbons having a good high density property.

According to the evaluation results shown in Table <NUM>, samples having good connection workability and a high density property (samples having the evaluation A or the evaluation S) were No. <NUM> to No. <NUM>. As a result, it was found that both the connection workability and the high density property of the intermittent connection-type optical fiber ribbon were good when the catenary amount H was <NUM> or more and <NUM> or less.

In order to further increase a core density, an increase in the Young's modulus of the secondary resin <NUM> of the optical fiber was discussed. As a result, it could be confirmed that each of the core densities shown in the column of high density property in Table <NUM> can be improved by about <NUM> core/mm<NUM> when the secondary resin <NUM> uses a resin having a Young's modulus of <NUM> MPa at <NUM>. Therefore, it was found that when the Young's modulus of the secondary resin <NUM> was set to <NUM> MPa and the catenary amount H of the intermittent connection-type optical fiber ribbon was set to <NUM> or more and <NUM> or less, the connection workability and the high density property were further improved.

In a case where the same <NUM>-core optical fiber ribbon as those in the samples No. <NUM> to No. <NUM> were used and an intermittent pattern was for every four cores, both the connection workability and the high density property were good when the catenary amount H was <NUM> or more and <NUM> or less.

Claim 1:
An intermittent connection-type optical fiber ribbon (<NUM>, <NUM>, <NUM>) comprising:
a plurality of optical fibers (<NUM>, <NUM>, <NUM>) that includes a connected section (<NUM>, <NUM>, <NUM>) in which adjacent optical fibers (<NUM>, <NUM>, <NUM>) of the optical fibers (<NUM>, <NUM>, <NUM>) are connected to each other, and a non-connected section (<NUM>, <NUM>, <NUM>) in which adjacent optical fibers (<NUM>, <NUM>, <NUM>) are not connected to each other, the connected section (<NUM>, <NUM>, <NUM>) and the non-connected section (<NUM>, <NUM>, <NUM>) being intermittently provided in a longitudinal direction of the plurality of optical fibers (<NUM>, <NUM>, <NUM>) in a part or all of places between the plurality of optical fibers (<NUM>, <NUM>, <NUM>) in a state where the plurality of optical fibers (<NUM>, <NUM>, <NUM>) are arranged in a direction orthogonal to the longitudinal direction,
wherein an outer diameter of each of the plurality of optical fibers (<NUM>, <NUM>, <NUM>) is <NUM> or more and <NUM> or less,
wherein each of the plurality of optical fibers (<NUM>, <NUM>, <NUM>) include a glass fiber (<NUM>) and a two-layer coating layer that covers a periphery of the glass fiber (<NUM>),
wherein an inner coating layer of the two-layer coating layer is formed of a primary resin (<NUM>),
wherein an outer coating layer of the two-layer coating layer is formed of a secondary resin (<NUM>),
wherein the secondary resin (<NUM>) has a Young's modulus of <NUM> MPa or more at <NUM>, and
wherein when the intermittent connection-type optical fiber ribbon (<NUM>, <NUM>, <NUM>) is held in a horizontal direction at a section from a position which is <NUM> away from a tip of the intermittent connection-type optical fiber ribbon (<NUM>, <NUM>, <NUM>),
characterized in that a connected section ratio is <NUM> or more and <NUM> or less, wherein the connected section ratio represents a ratio of a length of the connected section to a length of the non-connected section in the longitudinal direction of the intermittent connection-type optical fiber ribbon, and in that a deflection amount of the tip of the intermittent connection-type optical fiber ribbon (<NUM>, <NUM>, <NUM>) that protrudes from a held section is <NUM> or more and <NUM> or less in a direction orthogonal to the horizontal direction.