Winding – tensioning – or guiding – Reeling device – Multiple windings
Reexamination Certificate
1999-11-16
2001-11-27
Rivera, William A. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
Multiple windings
C385S135000, C385S137000
Reexamination Certificate
active
06322019
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of optical fiber storage systems.
BACKGROUND OF THE INVENTION
In a submarine optical communication system, optical signals communicated through the submarine optical fiber cable become attenuated over the length of the cable, which may stretch thousands of miles. To compensate for this signal attenuation, optical repeaters are strategically positioned along the length of the cable.
FIG. 1
illustrates a perspective view of a typical submarine optical repeater
10
having a cylindrical housing
12
. A first submarine optical cable
16
enters repeater
10
at first end cover
14
and connects to first internal optical cable
18
, which, in turn, connects to an optical repeater assembly
20
. Optical repeater assembly
20
typically includes at least the following items (not shown in FIG.
1
): optical components, connecting optical fibers, electronic circuits, and connecting wiring. Optical repeater assembly
20
connects via a second internal optical cable
19
to a second submarine optical cable
17
, which exits repeater
10
at second end cover
15
.
Typically, the optical fibers found within optical repeaters are circular in cross-section, and are constructed of glass surrounded by a protective jacket that is thicker than the glass. For example, a typical glass fiber (“glass fiber”, “bare fiber”, or “unjacketed fiber”) can have an outer diameter of approximately 0.010 inches, and a typical jacketed fiber can have an outer diameter of approximately 0.040 to 0.060 inches.
The glass fiber is fragile. Because even microscopic damage to the glass fiber can adversely affect the reliability of the optical repeater (and, as a result, the reliability of the entire submarine optical fiber cable system), great efforts are normally taken to protect the glass fiber from damage. Generally, the likelihood of damage to the glass fiber can be reduced by ensuring that any curvature in the glass fiber meets or exceeds the minimum bending radius of the glass fiber. However, the minimum bending radius of the glass fiber is a function of the expected life of the glass fiber. For example, when at least a 25-year life is expected, the glass fiber typically has a minimum bending radius of approximately 1 inch. This is referred to as the reliability-adjusted minimum bending radius of the glass fiber, because meeting or exceeding this value provides acceptable reliability from bending damage during the expected life of the glass fiber.
Typically, the optical components found within optical repeaters are manufactured with a segment of optical fiber attached at each end and cut to a specified length. Each fiber segment contains a jacketed portion of specified length located adjacent to the optical component, and a bare portion of specified length extending from the opposite end of the jacketed portion. The bare portion is spliced into the bare portion of another segment in the repeater's optical circuit. Creating these splices can be a complicated task, requiring substantial lengths of bare fiber on each side of the splice. Optimally however, the repeater is designed to be as space-efficient as possible, thereby minimizing its production, storage, shipping, and installation costs. Thus, it is desirable to store each optical fiber segment in the most space-efficient manner possible.
FIG. 2
illustrates a perspective view of a known fiber storage device that can be located within, for example, a submarine optical repeater or branching unit. Tray
42
includes generally circular portal spool
44
which is surrounded by generally square portal well
48
. The square portal well includes a fiber portal
68
. Tray
42
also includes generally circular storage spool
46
which is surrounded by generally square storage well
50
. Optical device
54
is mounted to tray
42
in optical cavity
52
which is connected to storage well
50
by cavity-to-storage channel
58
and by storage-to-cavity channel
64
. Optical cavity
52
is connected to portal well
58
by portal-to-cavity channel
72
and cavity-to-portal channel
66
.
Optical device
54
is connected to jacketed storage fiber
56
at the end of optical device
54
nearest storage well
50
. Just inside storage well
50
, jacketed storage fiber
56
connects to bare storage fiber
59
. The end of bare storage fiber
59
is spliced to the end of bare connecting fiber
60
at splice
74
. Bare connecting fiber
60
extends from splice
74
to jacketed connecting fiber
62
which., in turn, extends through storage-to-cavity channel
64
, through optical cavity
52
, through device-to-portal cavity
66
, and into portal well
48
. Within portal well
48
, jacketed connecting fiber
62
wraps around portal spool
44
and exits at portal
68
.
Jacketed connecting fiber
70
exits from the opposite end of optical device
54
and extends through portal-to-cavity channel
72
, and into portal well
48
, where it wraps around portal spool
44
and exits at portal
68
. Spools
44
and
46
are designed with a radius greater than or equal to the reliability-adjusted minimum bending radius of the bare portion of fibers
56
and
60
.
Although not shown, tray
42
can define more than one optical cavity and accompanying channels. In that situation, each additional optical fiber of any additionally mounted optical devices is routed and stored similarly to fibers
56
,
59
,
60
,
62
, and
70
, i.e., in the channels connected to their respective optical cavity and around their respective spools. When more than one fiber is to be spooled around either spool
44
or
46
, each additional fiber is wrapped around the spool generally above the preceding fibers, thereby forming a stack of spooled fibers.
Absent a late-stage design modification, jacketed fibers are generally not allowed to substantially intrude into the well where bare fiber is spooled, because such an intrusion can cause a jacketed fiber to press against or be spooled with a bare fiber. This is disadvantageous because the diameter of the jacketed fiber is much smaller than the reliability-adjusted minimum bending radius of the bare fiber. Thus, if the bare fiber is bent against the jacketed fiber, a violation of the minimum bending radius of the bare fiber can result, potentially causing unacceptable mechanical stresses in the bare fiber. Such a situation is particularly likely when a number of spooled bare fibers are stacked on a spool, and each fiber must be pushed down into the well to make room for the successive fibers, the pushing action thereby greatly increasing the forces bending the bare fiber around the intruding jacketed fiber.
When intrusion is unavoidable, the jacketed portion may only extend into the well when the well has sufficient space to prevent the intruding jacketed portion from contacting the spooled bare portion. This means that the jacketed portion may typically intrude into the well by no more than about 1 inch. If the jacketed portion will intrude by more than about 1 inch, the tray design, or more typically the optical component design, should be modified to avoid damage to the bare fibers. However, when design changes substantially affect fiber portion lengths, other difficulties can ensue.
Changes in the length of the bare fiber portion can sometimes be accommodated by adjusting the amount of bare fiber wound around the spool, or adjusting how tightly the bare fiber is wound around the spool. However, an increase of more than 1 inch in the length of the jacketed fiber portion typically requires a change to the optical component's manufacturing specification, because, as discussed previously, such an increase could cause the jacketed fiber to intrude excessively into the bare fiber storage area. Likewise, a decrease in the jacketed fiber's length could cause the bare fiber to be stored, unprotected, in a fiber channel, where it could be scratched by contact with the channel, or could be bent against an edge of the channel or another jacketed fiber.
As previously discussed, these types of situation
Rivera William A.
TyCom (US) Inc.
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