Optical waveguides – Accessories – Splice box and surplus fiber storage/trays/organizers/ carriers
Reexamination Certificate
1998-10-30
2001-03-27
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Accessories
Splice box and surplus fiber storage/trays/organizers/ carriers
C385S134000, C385S135000
Reexamination Certificate
active
06208797
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an optical fiber routing device and more particularly to a device for routing optical fibers for interconnection with a printed circuit board.
2. Description of the Related Art
The use of optical fibers to transmit high speed data signals is becoming more and more common. Glass fibers are used to route transmit signals long distances, perhaps between countries. Polymeric fibers are used for much shorter distances, where signal attenuation is not a problem. For example, in a telephone switching office, the various switching components are split onto different printed circuit boards. Polymeric optical fibers may be used to route the signals between the different circuit boards.
FIG. 1
is a perspective view of a conventional printed circuit board
8
and the apparatus for interconnecting an optical fiber therewith. Printed circuit board
8
is generally placed in a shelf or rack alongside other such circuit boards. Electrical contacts
12
connect with corresponding contacts at the back of the shelf. Circuit board
8
is secured into place with a pair of locking devices
14
.
In
FIG. 1
, optical fibers are first received by reception ports
2
. Then, optical fiber pieces
4
are used for transferring signals between reception ports
2
and electro-optical converters
6
. The optical fiber pieces
4
generally come in three and six foot lengths with connectors
5
provided at the ends thereof. However, printed circuit board
8
may have a width of only several inches. To accommodate for the extra length in the optical fiber pieces
4
, they are channelled around the circuit board
8
as shown in FIG.
1
. Clips
10
are used to secure the optical fiber pieces
4
to the printed circuit board
8
.
With increasing desire for greater integration, the space on circuit board
8
has become expensive. To secure the clips
10
to circuit board
8
, holes, perhaps four or more holes, must be drilled through the circuit board
8
. With four holes each having a three eights inch diameter, this consumes about 0.44 square inches of space. The components on the circuit board are connected together with traces above and within the board. The length of a trace may be limited by signal degradation or loss of speed problems associated with longer lengths. Wherever a hole appears in the circuit board for a clip
10
, a trace cannot be placed. If the trace has a limited length, placement of the components connected by the trace can be complicated. Furthermore, with the configuration shown in
FIG. 1
, the optical fiber pieces
4
run immediately adjacent to the printed circuit board
8
. Only small components can fit under optical fiber
4
. Large components would disturb the routing. That is, the optical fiber
4
has a minimum bend radius, and if bent beyond the minimum bend radius, signal degradation will result. Nine linear inches (the circumference of the circle of fiber) of fiber may be required to loop the fiber around to take up slack without bending beyond the minimum bend radius. Over this distance, the height of components is limited.
Designing where to place clips
10
also poses a problem. If it is necessary to move one clip
10
because of a trace intersection, for example, all other clips
10
must be also moved. To simultaneously find four acceptable places for all clips
10
represents a problem.
Once the printed circuit board
8
is designed with the layout of the components and the holes for clips
10
, assembly can be difficult. To assemble the device, the fiber optic pieces
4
are generally routed, by hand, through the clips
10
. As mentioned above, the optical fiber pieces cannot be bent beyond the minimum bend radius. Whether this requirement is satisfied depends on the individual operator doing the assembly.
As an alternative to the configuration shown in
FIG. 1
, it has been proposed to mount clips
10
to a unit which in turn is mounted to the printed circuit board
8
. The purpose of this device is to minimize the number of holes that must be formed through printed circuit board
8
. However, this device also increases the height above the printed circuit board
8
at which the optical fiber pieces
4
are routed. In
FIG. 1
, reference numerals
11
represents standoffs. A smaller circuit board is mounted to the standoffs
11
. If a separate device is used for mounting clips
10
, the height of the routing extends beyond the bottom of standoffs
11
and interferes with connection of the smaller circuit board.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to minimize the area on the printed circuit board consumed by holes for routing optical fibers.
It is a further object of the present invention to avoid component height restrictions where optical fibers are to be routed.
It is another object of the present invention to ease the layout design of a printed circuit board.
It is yet another object of the present invention to ensure that optical fibers are routed without bending beyond the minimum bend radius thereof.
It is still a further object of the present invention to provide a device that allows optical fibers to be routed and does not interfere with mounting a smaller circuit board above a main circuit board.
These and other objects are accomplished by providing an optical fiber routing unit which mounts to a circuit board with a hole formed therein. This routing unit has an oval shaped inner and outer channels separated by an oval shaped separating wall, extension supports and a standoff. The oval shaped inner channel has a radius at least as large as a minimum bend radius of a polymeric optical fiber. The oval shaped outer channel follows the inner channel, but has a larger radius than the inner channel. The oval shaped separating wall has a plurality of openings formed therein where passage between the inner and outer channels is possible. The extension supports extend between the opposing sides of the inner channel. The extension supports meet at an intersection thereof, and a connection hole is formed at the intersection where the extension supports meet. The standoff is removably secured to both the hole in the circuit board and the connection hole formed at the intersection of the extension supports. The standoff has a height that separates the circuit board from the inner and outer channels, the separating wall and the extension supports. To connect an optical fiber, the fiber is routed around the outer channel, crossed from the outer channel to the inner channel at an opening in the separating wall and routed around the inner channel.
REFERENCES:
patent: 4765708 (1988-08-01), Becker et al.
patent: 4861134 (1989-08-01), Alameel et al.
patent: 5142661 (1992-08-01), Grant et al.
patent: 5237640 (1993-08-01), Pedraza et al.
patent: 5311612 (1994-05-01), Vincent et al.
patent: 5329067 (1994-07-01), Abe et al.
patent: 5442726 (1995-08-01), Howard et al.
patent: 5469526 (1995-11-01), Rawlings
patent: 5659641 (1997-08-01), DeMeritt et al.
patent: 5689606 (1997-11-01), Hassan
patent: 5987207 (1999-11-01), Hoke
Richco, “Optical Fiber Support Base (OFSB)”, catalog excerpt (19 ).
DeFrancesco Marc
Vanderhoof Michael David
Doan Jennifer
Fujitsu Network Communications, Inc.
Sanghavi Hemang
Staas & Halsey , LLP
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