Technical Field
[0001]
The present invention relates to optical fiber units and
optical fiber unit manufacturing methods.
10
Background Art
[0002]
Techniques are known in the art for constructing an optical
fiber cable by bundling a plurality of optical fibers into
15 optical fiber assemblies as optical fiber units. This technique
typically involves winding a rough winding string (bundling
member) around each bundle of optical fibers, to thereby suppress
the optical fiber bundle from falling apart and enable each
optical fiber unit to be identified by the color of the bundling
20 member. For example, Patent Literature 1 discloses a technique
of forming an optical fiber unit by bundling together a plurality
of optical fiber ribbons.
Citation List
25 Patent Literature
[0003]
Patent Literature 1: Japanese Patent Application Laid-open
Publication No. 2007-233252A
30 Summary
Technical Problem
[0004]
In cases of constructing an optical fiber unit by bundling
a plurality of optical fiber ribbons, the optical fiber ribbons
35 may be bundled in a stacked state (i.e., in a state where the
3
plurality of optical fiber ribbons are superposed on one another),
as disclosed in Patent Literature 1. Unfortunately, in cases of
constructing an optical cable by using optical fiber units
including a plurality of optical fiber ribbons in a stacked state
5 as disclosed in Patent Literature 1, if a load (e.g., bending,
temperature change, etc.) is applied to the optical cable, the
load may concentrate only on certain optical fibers, which may
give rise to an increase in transmission loss.
[0005]
10 An objective of the present invention is to suppress load
from concentrating on certain optical fibers.

CLAIMS
[Claim 1] An optical fiber unit comprising
a plurality of intermittently-connected optical fiber
5 ribbons, wherein:
at least one of the plurality of optical fiber ribbons
comprises a plurality of optical fibers including
a first optical fiber, and
a second optical fiber that is longer than the first
10 optical fiber; and
conditions
and
c < 0.05
15 are satisfied, where b is an interval, in a length direction,
between connection parts that connect the first optical fiber
and the second optical fiber, c (%) is a fiber length difference
of the second optical fiber with respect to the first optical
fiber, and Y is an interval between the optical fibers in a
20 ribbon width direction.
[Claim 2] The optical fiber unit according to claim 1, further
comprising a bundling member that bundles the plurality of
optical fiber ribbons.
25
[Claim 3] The optical fiber unit according to claim 1 or 2,
wherein the second optical fiber is disposed asymmetrically with
respect to the ribbon width direction of the optical fiber ribbon.
30 [Claim 4] The optical fiber unit according to claim 3, wherein:
a first optical fiber ribbon and a second optical fiber
ribbon are disposed with respective ribbon surfaces facing one
36
another; and
when viewing the first optical fiber ribbon and the second
optical fiber ribbon from the length direction, a position, in
the ribbon width direction, of said second optical fiber in the
5 first optical fiber ribbon is different from a position, in the
ribbon width direction, of said second optical fiber in the
second optical fiber ribbon.
[Claim 5] An optical fiber unit manufacturing method
10 comprising:
preparing an intermittently-connected optical fiber ribbon
comprising a plurality of optical fibers including a first
optical fiber and a second optical fiber that is longer than the
first optical fiber, wherein conditions
15
and
c < 0.05
are satisfied, where b is an interval, in a length direction,
between connection parts that connect the first optical fiber
20 and the second optical fiber, c (%) is a fiber length difference
of the second optical fiber with respect to the first optical
fiber, and Y is an interval between the optical fibers in a
ribbon width direction; and
assembling a plurality of intermittently-connected optical
25 fiber ribbons including said optical fiber ribbon including said
second optical fiber.