Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- 2190815
Cable Containing Easily Ide~ ial~le Optical Ribbons
Background of the Invention
This invention relates to optical fiber telecommunication cables containing
optical fiber ribbons.
Telecommunication cables containing light waveguides, herein called
optical fibers, are now in widespread use in telecommunication networks. Some
telecommunication cables employ optical fibers in the form of an optical fiber
ribbon. An optical ribbon, as used herein, means a substantially planar array of
optical fibers enclosed by, mounted on, or embedded within a narrow, flat ribbon
or band of a polymer material, or joined in other ways by a material, such as by
edge bonding. Optical ribbons have a certain advantage in high fiber count
telecommunication cables, in that techniques are being developed to mass-
fusion splice optical ribbons to each other. Such mass splicing may help to
reduce installation costs in some network installations. The availability of multi-
fiber ribbon-to-ribbon connectors provides another advantage.
Any of a variety of cable designs may contain optical ribbons. The optical
ribbons may be housed in grooves located in the external surface of a cylindrical
rod. Optical ribbons may be located in a tube located at the central axis of the
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cable, or in a plurality of tubes arranged about a cable central tensile-resistant
member. In each case, each tube or groove may contain a stack of optical
ribbons.
If a cable is manufactured to contain a large number of optical ribbons, the
problem arises of identifying the individual ribbons and distinguishing the optical
ribbons from one another. One way to identify optical ribbons is by forming the
polymer tape or coating of a transparent material and coloring the outer surface
of the optical fibers of the ribbon. The optical fiber coatings may be colored, and
colored binder tapes or threads may be employed. However, some persons
cannot distinguish certain colors, and the coloration may be rather faint in order
to avoid deterioration of desirable properties of the optical fibers or optical
ribbons due to properties of the pigments.
The use of colors alone as an identifying means may be insufficient when
dealing with high fiber count cables. The problem is multiplied when using cables
employing splittable optical ribbons. One expedient which has been used is to
rely on the marking or positioning of tubes or carriers containing the ribbons or
ribbon stacks. Ring marking has been employed, as shown in U.S. Pat. No.
5,379,363 and the article "Stranding machines for optical fibre ribbon cables"
appearing in the Dec. 1994 edition of wire.
Printing words on ribbons has also been employed, also as shown in the
article appearing in wire referenced above. Most optical fiber ribbons are quite
narrow, however, rendering print difficult to read. Another difficulty is that words
are of less use when dealing with cables shipped between countries using
RIPI~) PAT 2
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different languages. None of these solutions is fully adequate to deal with the
problem of identifying and distinguishing large numbers of optical ribbons from
each other in high fiber count cables.
Summary of the Invention
It is therefore an object of the present invention to provide means for
adequately identifying large numbers of optical ribbons and for distinguishing
them from each other by inspection of the ribbons alone, without reliance on
positional information.
It is another object of the present invention to provide identification means
which do not depend on the presence of colors or printed words.
Still another object of the invention is to provide identification means which
may be commonly employed in areas using different spoken languages.
These and other objects are provided, according to the present invention,
by an optical fiber ribbon cable containing ribbons having improved means for
identification .
Cables according to a first embodiment of the invention contain optical
fiber ribbons marked with a binary code.
Cables according to a second embodiment of the invention contain optical
fiber ribbons marked with a machine-readable bar code.
Optical fiber ribbons of either embodiment may comprise splittable
subunits, each subunit being separately coded for further identification.
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2190815
Brief Description of the Drawings
The invention is described with reference to the several drawings, in
which:
FIG. 1 is a cross-sectional view of a cable according to the invention
containing coded optical fiber ribbons;
FIG. 2 is a perspective view of a splittable optical fiber ribbon comprising
binary-coded subunits;
FIG. 3 is a perspective view of a splittable optical fiber ribbon comprising
bar-coded subunits;
FIG. 4 is a cross sectional view along lines 4-4 of FIG. 2;
Fig. 5 is a stack of binary coded optical fiber ribbons; and,
Fig. 6 is a stack of bar coded optical fiber ribbons.
Detailed Description of the Invention
The present invention will now be described more fully hereinafter with
reference to the accompanying drawings, in which one or more preferred
embodiments of the invention are shown. This invention may, however, be
embodied in many different forms and should not be construed as limited to the
embodiments set forth herein; rather, these embodiments are provided so that
the disclosure will fully convey the scope of the invention to those skilled in the
art. Like numbers refer to like elements throughout. The drawings are not
necessarily drawn to scale but are configured to clearly illustrate the invention.
Cable 10 as shown in Fig. 1 contains a core tube 28 formed of plastic
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Brief Description of the Drawings
The invention is described with reference to the several drawings, in
which:
FIG. 1 is a cross-sectional view of a cable according to the invention
containing coded optical fiber ribbons;
FIG. 2 is a perspective view of a splittable optical fiber ribbon comprising
binary-coded subunits;
FIG. 3 is a perspective view of a splittable optical fiber ribbon comprising
bar-coded subunits;
FIG. 4 is a cross sectional view along lines 4-4 of FIG. 2;
Fig. 5 is a stack of binary coded optical fiber ribbons; and,
Fig. 6 is a stack of bar coded optical fiber ribbons.
Detailed Description of the Invention
The present invention will now be described more fully hereinafter with
reference to the accompanying drawings, in which one or more preferred
embodiments of the invention are shown. This invention may, however, be
embodied in many different forms and should not be construed as limited to the
embodiments set forth herein; rather, these embodiments are provided so that
the disclosure will fully convey the scope of the invention to those skilled in the
art. Like numbers refer to like elements throughout. The drawings are not
necessarily drawn to scale but are configured to clearly illustrate the invention.
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Cable 10 as shown in Fig. 1 contains a core tube 28 formed of plastic
material loosely surrounding ten optical fiber ribbons 12. A filling compound 27
occupies the portion of the interior of tube 28 which is not occupied by ribbons
12. Surrounding tube 28 is a water-swellable tape 29. Overlying tape 29 is an
aramid yarn ripcord 30, which underlies a steel tape armor 31. Armor 31 is
secured by adhesive 32 to outer jacket 35, which is formed of plastic material.
Steel wires 34 are embedded 180 degrees apart from each other within outer
sheath 35 near its inner surface. Ripcords 33 are disposed between armor 31
and outer sheath 35.
Cabies according to the invention may contain at least two optical fiber
ribbons, and may contain over one hundred optical fiber ribbons 12 which must
be distinguishable from each other. A cable according to the invention may also
contain at least one optical fiber ribbon having a plurality of ribbon subunits. Of
course, the invention is not limited to the single tube design of FIG. 1; coded
ribbons may be inserted into other cable designs such as slotted core-type
cables, stranded tube type cables, or cables having U-shaped carriers, by way of
example. Cable 10 may contain binary coded optical fiber ribbons as shown in
Fig. 2 or 5 or bar coded optical fiber ribbons as shown in Fig. 3 or 6 and
discussed hereafter.
An optical fiber ribbon 12 according to a first embodiment of the invention
shown in FIG. 2 comprises detachable ribbon subunits 21, 22, each having
separate binary coding thereon. The binary coding preferably avoids the use of
arabic numerals or alphabetic characters, and may be in the form of rectangles
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2190815
.
as shown. Ribbon subunit 21 bears binary code 19, and ribbon subunit If~2 bears
binary code 20. Ribbon subunit 21 contains a plurality of optical fibers 26, and
subunit 22 contains a plurality of optical fibers 14. Optical fibers 14, 26 may each
have a different surface coloring 38 thereon to enable the optical fibers to be
distinguished from each other. The optical fiber coloring should be light in order
not to interfere with reading tf~e ink coding. The ribbon subunit matrix material
17, 18 (see ~ig. 4) may be formed of a transparent or translucent acrylate
material cured by ultraviolet light. Matrix material 171 18 should be formed of a
material which allows the optical fiber colors to be seen, yet provides a suitable
background against which the binary codes may be interpreted. The optical
fibers may be disposed to be spaced apart from each other or in side-to-side
contact, such as through edge bonding.
A ribbon subunit may be respooled after the subunit is made by forming à
common coating such as 17, 18 around the optical fibers. An ink jet printer may
then be used to print a short string of characters on the exterior surface of the
common subunit coating by using a binary code font in a periodic fashion along
the length of the ribbon subunit. A coding scheme should be selected such that
each ribbon subunit may be distinguishable from the others. This may be
accomplished by printing in a five character string binary font, with a dot
representing "0" and a dash representing "1". Suitable ink jet printers may be
obtained from Video Jet Systems International, Inc. of Elk Grove Village, Illinois,
using type "8900" printing ink.
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2190815
After the coding is imprinted, each subunit 21, 22 may then be covered by
a common coating 25 of transparent or translucent material cured by ultraviolet
light. Examples of such materials are matrix coating 314-200-3 supplied by
Borden, Inc. and CableLite 3287-9-77 supplied by DSM Desotech Inc. The
subunit binary character strings should be spaced apart longitudinally with
respect to each other as shown in Fig. 2 so that they will be more easily read.
Another optical fiber ribbon 12' according to a second embodiment of the
invention shown in Fig. 3 comprises ribbon subunit 21, bearing machine-readable
bar coding 23, and ribbon subunit 22, bearing machine-readable bar coding 24.
Respooled bar coded ribbon subunits may be coded by printing thereon a string
of less than ten characters using a USS-39 (CODE 39) bar code symbology in a
periodic fashion along the length of the ribbon. This results in a field of not less
than three and not more than twelve characters, including start and stop
characters. Optical fiber ribbons 12 and 12' are similar in other respects. The
construction of optical fiber ribbon 12' shown in Fig. 3 is the same as the
construction of optical fiber ribbon 12 shown in Fig. 4, with the substitution of bar
coding 23, 24 for binary coding 19, 20. Processing of optical fiber ribbons 12 and
12' is also generally similar.
In either embodiment, each ribbon subunit should have a code unique in
that cable.
In constructing optical fiber ribbons which are to be identifiable by bar
coding, character recognition by print contrast signal (PCS) may be used. In
PCS-based methods, the percentage reflectance of spaces between the inked
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symbols is compared with the reflectance of the inked symbols. The narrowest
bars in the inked symbols are referred to as the nominal narrow elements. The
minimum reflectance within any space or quiet zone should be 25 percent, and
the maximum reflectance of any bar should be 25 percent. The PCS is the
difference between these two values and ideally should be at least 75 percent If
the nominal narrow elements have a width of 0.508 mm or less, the minimum
reflectance of the spaces should be at least 50 percent, and should be at least 25
percent if the width of the nominal narrow elements is more than 0.508 mm.
Some inks used for coloring optical fibers may not have sufficient
reflectance for use with particular bar code reading machines. Orange, white,
red, yellow, violet, and pink inks have been found to provide a more suitable
background than blue, green, brown, and black inks. An adjustment in the
percentage of pigment used may be necessary in some instances.
An example of bar coding which may be employed is AIM uniform
symbology specification USS-39 (CODE 39) having a nominal narrow element
width of 0.4 inches. Of course, other symbologies and element widths may be
used.
A hand-held bar code reading machine may be used to interpret the bar
coding. The use of strings having a length of less than ten characters allows the
user to read the codes more easily in the field
The binary or bar codes are preferably applied by an ink jet printing
device, but any suitable printing device may be used that provides coding
characters that are sufficiently clear and distinct. Each binary or bar code
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2190815
preferably is printed in periodic fashon throughout the length of the ribbon, and
each code repetition preferably may be preceded by a recognition symbol such
as shown in Fig. 2. If the sul~slrate material is dark, the binary or bar coding may
be formed by printing a light background, with the bars formed by substrate areas
with no printing thereover.
Whether or not an optical fiber ribbon contains ribbon subunits, binar~ or
machine-readable bar coding may be printed on the exterior surface of a
common ribbon coating. Either splittable ribbon subunits or nonsplittable optical
fiber ribbons may be coded. A stack 36 of nonsplittable optical fiber ribbons
containing binary coding is shown in Fig. 5, and a stack 37 of nonsplittable optical
fiber ribbons is shown in Fig. 6. The stacks of either Fig. 5 or Fig. 6 may be
employed in cable 10.
It is to be understood that the invention is not limited to the exact details of
the construction, operation, exact materials, or embodiments shown and
described, as modifications and equivalents will be apparent to one skilled in the
art without departing from the scope of the invention.
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