Note: Descriptions are shown in the official language in which they were submitted.
~751~t~B
BACKGROUND OF THE INVENTION
The present invention is directed to a precision
part for optical waveguide connectors for the purpose of con-
necting of either a single or multiple fibers of cables which
precision part includes a connector cylinder having a recess
for optical waveguides and an insert received in the recess.
Presently, single optical waveguide connectors are
being manufactured which have an optical waveguide fiber admis-
sion opening drilled in a bushing consisting of a material hav-
ing good machining properties. I'his bushing is pressed into
the connector part which is fabricated of low-wear, abrasion-
proof material such as disclosed in Gebrauchmuster (German
Utility Model) 81 19 993. Published November 5, 1981. However,
connectors are also manufactured as a one-piece member consis-
ting of a material having the good machining properties.
It has also already been proposed to concentrically
adjust and then cement a capillary tube in a connector part by
means of adjusting mandrels or pins. In the case of optical
waveguide connectors, it is also known for the connector cylin-
ders to be aligned according to the fiber cores and cast or sub-
sequently machined.
From German Patent 28 32 303, Published April 8, 1982
a method is known wherein a horological stone is cemented in the
connector cylinder and subsequently the connector cylinder after
the fiber insertion ls subsequently machined concentrically.
SUMMARY OF THE INVENTION
The present invention is directed to manufacturing
precision parts for single and/or multiple optical waveguide
connectors in a more economical fashion than up to the present
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time. In so doing, primarily their coaxiality between connector
cylinder, exterior diameter and the optical waveguide as well as
the fiber emission openings is to be very precise. Moreover, it
is demanded that diameter tolerances of the connector cylinders
and the fiber admission openings are likewise very low in order
that a low coupling attenuation between random optical fiber
connector pairings is obtained.
To obtain these objects, the present invention is
directed to an improvement in a precision part for an optical
waveguide connector for the purpose of a connection between
cables having either single or multiple waveguides, the precision
parts consisting of a connector cylinder having a recess for the
optical waveguides and an insert. The improvements are that the
insert consist of one or more self-centering electroplated parts,
which have been termed by an electroplating process, with each
part having an optical waveguide admission opening of random
geometry. The connecting cylinder is a separately fabricated
connector cylinder and the electroplated parts are mounted in the
recess of the connector cylinder.
Through this solution, an extremely precise design is
achieved even in the case of mass production. For the
manufacturing of flat parts for which, on account of the demands
for precision, the chemical etching technique is no longer
sufficient, most frequently the electroplating method is
utilized. A glass mask with a one-sided metallization in which
the image is to be formed is manufactured. Then a negative
resist is applied on the side of the metallization and
subsequently exposed to ultraviolet light. The non-exposed
locations are developed out and the exposed metallization is
galvanically coated so that electroplating results. Thereafter,
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the electroplated portion is detached from the glass mask and
cleaned of the resist. The thickness and contour quality of the
electroplated portions are restricted by the thickness and the
edge qualities of the photoresistant layer. The possible
fineness and quality of the resist structure decreases with the
resist thickness.
~ ithin the framework of the invention, the electroplated
parts can exhibit optical waveguide admission openings which have
a square, round or triangular geometry. Through the freely
selectable geometry of the fiber emission openings, the fit or
play between fiber admission opening and fiber can be kept
especially small.
According to a further development of the invention, the
admission opening has walls with an angle of slope. The
threading-in of the fiber is thereby substantially facilitated by
the tapering walls of the opening.
The self-centering electroplated parts, which are
inserted in the connector cylinder, are preferably manufactured
from copper or nickel.
According to a further embodiment of the invention, the
connector cylinder is fabricated from an abrasion-proof material,
for example V2A steel and is equipped with precise external and
internal diameters. This has the advantage that the connector
cylinder does not show any wear even after many or frequent
operations or actuations.
The inserts or electroplated parts, for example, are
pressed into the connector cylinder of abrasion-proof material
and the glass fibers are cemented or soldered into the admission
openings. This precision part is the ground and polished at the
coupling side. If the admission opening has a form different
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from the fiber form, the cement can more readily penetrate the
spaces and can therefore guarantee a reliable fixation of the
glass fiber.
According to a further development of the invention, the
exterior diameter of the insert assumes the centering of the
fiber in the counterpiece. Through this embodiment, the glass
fibers are centered in the coupling sleeve directly by the
electroplated part.
According to another development of the invention, the
part or parts are provided with radially extending side bars or
portions which engage in corresponding grooves of the connector
cylinder. The radial side bars have a diameter which is greater
than or equal to the diameter of the connector cylinder. This
embodiment renders it possible to obtain a particularly easy
assembly of the parts. Due to the special design of the
connector cylinder and the insert, the required precision is
achieved solely through the inserts. The connector cylinder can
be fabricated with a lesser degree of precision so that this
design is particularly economical.
For the connection of multifiber cables with a random
number of optical waveguides, the optical waveguide admission
openings are preferably arranged annularly on the border of the
parts. In addition, to the distribution of the admission
openings about the circumference of the part, the part should be
provided with at least two larger openings for positioning
pins. In this manner, it is possible to connect many fibers in
the narrow space. The other connector parts are so designed that
the cable length is taken up by the housing and the glass fibers
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are simple to introduce through the fiber guide slots into the
connector.
Within the framework of the invention, the electroplated
parts can also be designed with an angular cross-section. In
addition, the fiber admission openings can be randomly arranged
in the electroplated part.
In summary, it can be stated that the following
advantages result from the invention. The electroplated parts of
the invention enable an economical mass fabrication of parts with
a high precision. The electroplated or electroformed parts
provide positive connections in a radial direction between the
connector cylinder and inserts and between the fiber emission
openings and the glass fibers. The forming of the part by
electroplating enables an optimum design of the openings for the
fiber, the fiber guide and the fiber precentering. Through
stacking of the inserts, greater guide lengths are attainable for
the glass fibers than in the case of drilled connectors. The
coupling attenuation of the optical waveguide connector pairs is
strongly influenced by errors or offsets in alignment, surface
roughness and the distance between the fiber cores. The error in
the alignment is brought about by the diameter tolerances of the
connector cylinders, the fiber admission openings and the optical
waveguide fibers as well as by the deviation from the
concentricity between the fiber core and connector cylinders.
The invention, through the special design of the
precision part, solves the technical problem of manufacturing two
precise cylinders coaxial in one part because the connector
cylinder is separately fabricated and subsequently the self-
centering electroplated parts which are formed by electroplating
are mounted in the connector cylinder. These electroplated parts
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have, for example, quadratic or square optical waveguide openings
so tha~ the or play between the glass fiber and the opening can
be greatly reduced. In addition, large free spaces result at the
corners in which the bonding agent such as a cement or solder can
more easily penetrate than in the case of known cylindrical
admission openings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. la is a longitudinal cross-sectional view with
portions in elevation of a single connector with disk-shaped
inserts having different geometry;
FIG. lb is an end view of the device of FIG. la;
FIG. 2a is a longitudinal cross-sectional view with
portions in elevation for purposes of illustration of an
embodiment of a single connector having inserts;
FIG. 2b is an end view of the connector of FIG. 2a;
FIG. 3a is a longitudinal cross-sectional view with
portions in elevation of a connection according to the present
invention for coupling cables with multiple fibers together; and
FIG. 3b is an end view of a part of the connector in a
disconnected condition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The principles of the present invention are particularly
useful in a single connector generally indicated at 50 in FIGS.
la and lb. The connector 50 has a connector cylinder 1 which has
a hollow cylindrical cavity or recess 2 which receives a part 51
having a tapering guide core 3 with a cylindrical portion 3a. As
illustrated, the part 51 is set in from an end of the cylinder 1
and the space between the end of the cylinder and the member 51
receives a plurality of inserts 5 which as illustrated consist of
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four parts. The four parts or inserts are electroplated parts
which have concentric openings for receiving a fiber 6 with its
coating 7 removed therefrom. As illustrated, the openings in the
parts 5 are substantially smaller than the opening 3a of the part
51. As illustrated, the fiber 6 with its coating 7 also is
provided with a fiber sheath or shell 8. The threading-in of the
glass fiber is facilitated at the innermost part 5' which is
provided with tapered bevels 9 at its opening. Thus, the opening
with the bevel 9 facilitates guiding the fiber 6 as it is
inserted through the remaining admissicn openings such as
admission opening 11 illustrated in FIG. lb. As illustrated in
FIG. lb, the admission opening 11 has a quadratic or square
configuration.
An embodiment of the connector is generally indicated at
53 in FIGS. 2a and 2b. The connector 53 has a connector cylinder
la which has a recess 54 large enough to receive the sleeve or
coating 7 of the fiber 6. Adjacent the end, the recess 54 has a
converging tapered portion or conical portion 55 which approaches
the diameter of the fiber 6. The end of the member la has a
counterbore portion 56 with three radial slots 57 which receive a
series such as four electroplated parts 5a which have a circular
portion 58 with three ~adially extending bars or legs 10 as best
illustrated in FIG. 2b. Each of the parts 5a has an admission
opening such as the opening 12 which is illustrated as having a
triangular configuration. The innermost bar 5a' is also provided
with converging walls to facilitate guiding the fiber 6 therein.
A coupling generally indicated at 60 in FIGS. 3a and 3b
is constructed to handle a cable having a plurality of light
waveguides such as glass fibers 19. The device includes a pair
of cylindrical connector parts 61 and 62, each of which have a
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coupling surface 16 and a cylindrical recess such as the recess
63 of the part 62. The recess 63 has step portions 64 opposite a
coupling surface 16. As illustrated, the portion 64 of the
recess 63 receives a stepped member 65 which has fiber guide
slots 20 on its circumference. ~Jext to the part 65 is a part 23
which is a precentering part that is provided with axially
extending bores 66 adjacent the periphery and these bores 66 line
up with ad~ission openings 13 in a part 18 which along with the
part 17 are electroplated parts. The part 18 besides having a
plurality of admission openings 13 around the periphery of the
part include some large bores 14 (FIG. 3b) which receives
positioning or centering pins 15 (FIG. 3a). By utilizing the
pins 15, the two parts 17 and 18 are axially aligned with their
openings such as 13, which receive the fibers 19, being
aligned. As mentioned hereinabove, the cable sleeve which is
references 22 has a plurality of optical fibers having a coating
21. These fibers are guided through the guide slots 20 to the
precentering part 23, the coating 21 is removed to expose only
the fibers 19. The fibers 19 are positioned to extend through
the bores 66 of the precentering part 23 and enter into the bores
or openings such as 13 of the part 18. After cementing the parts
in their various openings such as 13, the fibers are polished to
lie in the plane of the surface 16. The two connectors such as
61 and 62 can be brought together by external connecting parts
such as 67 and 68 and to prevent axial torsion or twisting
between the two parts 61 and 62, a spline such as 24 is provided.
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Although various minor modifications may be suggested by
those versed in the art, it should be understood that we wish to
embody within the scope of the part granted hereon, all such
modifications as reasonably and properly come within the scope of
our contribution to the art.
