Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-10-18
2002-04-09
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S179000, C156S273300, C156S273500, C156S275700, C385S052000
Reexamination Certificate
active
06368441
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing an optical fiber array that comprises a plurality of bare fibers aligned and held at specific intervals and that facilitates the optical and mechanical coupling of the bare fibers and connection elements (for example, optical fiber lines, optical waveguides, optical elements, and other components on optical circuit boards) in a facing arrangement therewith, and more particularly to a method for manufacturing an optical fiber array aimed at eliminating the need to provide bare fiber guide members and reducing manufacturing costs without lowering the accuracy of the alignment intervals between the bare fibers.
2. Description of the Related Art
With such optical fiber arrays, the alignment intervals between the bare fibers can be set with high accuracy, and positional matching and optical coupling can be facilitated in relation to the optical fiber lines, optical waveguides, and the like on optical circuit boards arranged at corresponding alignment intervals.
Bare fiber guide members for accurately setting the alignment intervals between bare fibers are provided to conventional optical fiber arrays as the structural members of these optical fiber arrays. In conventional practice, the V-groove member a depicted in
FIG. 25A
, the capillary member b depicted in
FIG. 26
, and the like are known as such bare fiber guide members.
Specifically, the aforementioned V-groove member a is configured such that a plurality of grooves with generally V-shaped cross sections (V grooves) al are formed lengthwise on one of the surfaces thereof.
Bare fibers c are placed in the V grooves a
1
of the aforementioned V-groove member a. The bare fibers c are secured in place by the two lateral inclined planes of the V grooves a
1
, and the fixing positions of these bare fibers c are set, by downward pressure from a presser plate d, as shown in FIG.
25
B.
A plurality of bare fibers c can be aligned at regular intervals by forming a plurality of identically sized V grooves a
1
at regular intervals. An optical fiber array e configured as shown in
FIG. 25C
is obtained by filling the gaps between the aforementioned bare fibers c (exposed fibers stripped of their outer envelopes, that is, fibers comprising a core and a cladding, are referred to as “bare fibers”; in a narrow sense, this term applies to exposed sections obtained by the stripping of the outer envelope from the area near the tip of a fiber ribbon), the V-groove member a, and the presser plate d with an adhesive and allowing this adhesive to solidify.
A capillary member b, on the other hand, is provided with a plurality of long and narrow holes b
1
whose inside diameter is slightly greater (commonly about 1-2 &mgr;m) than the outer contours of the bare fibers, as shown in FIG.
26
. The fixing positions of the bare fibers are approximately set by inserting the bare fibers into the holes b
1
. The gaps between the bare fibers and the holes b
1
are filled with an adhesive. The surface tension of this adhesive has an action whereby the bare fibers tend to be disposed roughly in the centers of the holes b
1
, and the bare fibers are fixed in the capillary member b by allowing the filled-in adhesive to solidify. The bare fibers and the wall surfaces of the holes b
1
in the capillary member b are not necessarily in contact with each other due to the presence of the aforementioned adhesive, but because the surface tension of the filled-in adhesive has an action whereby the bare fibers tend to be disposed roughly in the centers of the holes b
1
in the above-described manner, it is the wall surfaces of the holes b
1
that set the fixing positions of the bare fibers. Consequently, a plurality of bare fibers can be aligned at regular intervals by forming a plurality of holes b
1
whose centers are spaced at regular intervals.
It should be noted that the above-described V-groove member a, capillary member b, and other bare fiber guide members incur high manufacturing costs because these bare fiber guide members require high dimensional accuracy (commonly 1 &mgr;m or less). Another drawback is that conventional optical fiber arrays are provided with the above-described bare fiber guide members as the structural members thereof, so the cost of such optical fiber arrays is proportionally higher.
To overcome this shortcoming, a method (see Japanese Unexamined Patent Application, (Japanese Patent Laid-Open No.07-168047) has been developed in which two tabular members f
1
and f
2
(see
FIG. 27
) with generally L-shaped cross sections are used instead of the above-described V-groove member a, capillary member b, or the like; bare fibers c are confined between these tabular members f
1
and f
2
; and these bare fibers c are confined using an L-shaped ferrule with a generally L-shaped cross section and two flat plates parallel to two planes of this L-shaped ferrule.
This and other methods are disadvantageous, however, in that the alignment intervals between bare fibers cannot be set freely because these alignment intervals are determined by the diameters of the bare fibers. Another disadvantage is that when the diameters of the bare fibers vary as a result of dimensional nonuniformities, these nonuniformities accumulate and ultimately bring about marked variations in the fixing positions of the bare fibers in the areas near the two ends, making these methods unsuitable for reducing manufacturing costs without lowering the accuracy of the alignment intervals between the bare fibers.
By contrast, the bare fibers of optical fiber arrays provided with V-groove members a, capillary members b, and other bare fiber guide members are fixed individually, preventing the errors in the fixing positions from accumulating across a plurality of bare fibers.
A drawback, therefore, is that it is currently indispensable that the above-described V-groove members a, capillary members b, or other bare fiber guide members be provided in order to accurately set the alignment intervals between bare fibers, perpetuating the situation that prevents production of lower-cost optical fiber arrays.
With this technical background in view, a method for manufacturing an optical fiber array in which bare fibers can be aligned with high accuracy without the use of expensive bare fiber guide members has recently been proposed (see Japanese Patent Laid-Open No.06-11625).
Specifically, this manufacturing method entails installing a fiber-ribbon guide g, which is provided with a plurality of V grooves formed at an equal pitch in the upper surface thereof in the manner shown in
FIG. 28A
; a bare-fiber guide h (see FIG.
29
), which is provided with a plurality of V grooves formed in the upper surface thereof; and a presser i, which is provided with trapezoid projections that fit into the V grooves of the aforementioned fiber-ribbon guide g. The tip portions of fiber ribbons k (exposed sections obtained by stripping away the jackets j
1
of fiber optic cables j, that is, sections covered by ribbon material k
1
, are referred to as “fiber ribbons”) are inserted into the V grooves of the aforementioned fiber-ribbon guide g to support these fiber ribbons k in a parallel formation; the tip portions of bare fibers m (in a narrow sense, “bare fibers” refers to exposed sections obtained by stripping the ribbon material k
1
from the fiber ribbons k) are inserted into the V grooves of the aforementioned bare-fiber guide h to support the bare fibers m in a parallel formation; the aforementioned presser i is placed on the bare-fiber guide h to prevent the bare fibers m from shifting upward; and the external peripheral surfaces of the bare fibers m and fiber ribbons k are coated with an adhesive n.
According to this method, a bottom plate r (see
FIG. 30
) is then set such that a flat surface p is disposed underneath the bare fibers m in the manner shown in FIG.
28
B and that an angular groove q is disposed underneath the fiber ribbons k; a top plate s (see
FIG. 30
) is set such that a flat s
Aftergut Jeff H.
Armstrong Westerman & Hattori, LLP
Kilkenny Todd J.
Sumitomo Metal & Mining Co., Ltd.
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