Optical waveguides – Miscellaneous
Reexamination Certificate
2000-06-15
2004-08-17
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Miscellaneous
C385S014000, C156S158000, C156S166000
Reexamination Certificate
active
06778754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a manufacturing apparatus for optical fiber wiring boards.
The present specification is based on a Japanese patent application (Japanese Patent Application No HEI 11-171671), and the contents of this Japanese Patent Application are incorporated by reference as a part of the present specification.
2. Background Art
Optical fiber wiring boards collect wiring groups of optical fibers optically connecting a plurality of optical parts, as wiring parts, and in electrical circuit terms, correspond to printed wiring boards which are employed in electrical circuit wiring, or to backplanes, which are used to conduct wiring between boards or between apparatuses. Methods which are known as manufacturing methods for optical fiber wiring boards include methods in which the optical fibers are coated with an adhesive and are then pressure applied to the surface of a substrate to form the wiring.
Japanese Patent No. 2,735,464 (U.S. Pat. No. 5,259,051) discloses, with respect to the manufacture of optical wiring boards (termed backplanes) which optically connect boards on which optical parts are mounted, an optical fiber interconnection apparatus and method in which “[a] rotatable wheel is mounted on a free end of a manipulator” and “a peripheral portion of the rotatable wheel causes one end of the optical fibers to adhere to the adhesive coated surface of the substrate.”
Japanese Patent Application, First Publication No. HEI 7-181356 (U.S. Pat. No. 5,421,930) discloses an apparatus in which, in order to automatically wire optical fibers (pigtails) extending from optical devices onto a substrate, the stored optical fibers are wired onto an adhesive sheet by a rotatable wheel, termed a wiring wheel.
Japanese Patent Application No. HEI 9-281645 discloses, with respect to the structure of an optical wiring boards, a through hole which is provided in the lead end of a wiring head which bends an inserted optical fiber and, employing this stress, presses the optical fiber against an adhesive sheet and thus wires it.
In optical wiring boards, configurations are rare in which the wiring pattern of the optical fibers consists of parallel straight lines, and it is necessary to be able to conduct the wiring of free patterns in which the optical fibers bend and cross one another. Furthermore, it is necessary that the terminals of the optical fiber wiring boards have an arrangement which allows for multiconductors of optical part connectors so as to permit the direct connection of optical parts, in concert with an increase in integration, so that a wiring technique which accurately lines up optical fibers at a narrow pitch is extremely important.
The rotatable wheel, wiring wheel, and through hole described above are extremely important parts for the wiring of optical fibers on adhesive sheets, and these structures control the precision of the pattern and the degree of attachment to the substrate of the wiring.
The rotatable wheel of Japanese Patent No. 2,735,464 and the wiring wheel of Japanese Patent Application, First Publication No. HEI 7-181356 also have a structure in which a groove for supporting the optical fiber at a predetermined position is provided in the outer circumference of the rotatable wheel (wiring wheel). For this reason, in the wiring of a pattern having curved portions, when the rotatable wheel faces in the direction in which the pattern is proceeding, the optical fiber which is wired is compressed by the edge of the groove and becomes disordered, so that the optical fiber which has been caused to adhere to the substrate is likely to detach therefrom. This tendency becomes more pronounced as the radius of the curvature in the wiring pattern becomes smaller, or as the diameter of the rotatable wheel becomes larger.
In response to this, it is necessary that the radius of the rotatable wheel be set so as to be larger than the breakage curvature radius of the optical fiber which is wired (the breakage curvature radius of a commonly available single mode optical fiber core is approximately 2 mm), so that the optical fiber is not broken. Furthermore, in order to miniaturize the rotatable wheel, it is also necessary to miniaturize the bearing of the rotatable wheel which permits smooth rotation, and structurally, there Is a limit to such miniaturization.
Furthermore, in Japanese Patent No. 2,735,464, “as the manipulator moves, the rotatable wheel rotates as a result of friction, and by means of this, tension is exerted on the optical fiber, and by means of this, optical fiber is supplied from the reel on which the optical fiber is wound to the rotatable wheel, and is wired on the substrate,” so that in order to wire the optical fiber in the manner of the wiring pattern it is necessary to rotate the rotatable wheel by means of friction and to draw exactly that length of optical fiber provided for in the pattern from the reel. However, in actuality, it is extremely difficult to rotate the rotatable wheel in such a manner as to draw only that length of optical fiber provided for in the pattern.
That is to say, when an optical fiber is wired in such a manner as to cross over a previously wired optical fiber, as a result of friction with the previously wired optical fiber when passing over this fiber, the rotatable wheel rotates; at such times, it is thought that sufficient friction cannot be obtained. Furthermore, when wiring is conducted while curving and passing over an optical fiber, a force acts in a transverse direction with respect to the direction of progression, slippage is produced with the lower-side optical fiber, and there is a danger that sufficient friction will not be obtained.
Furthermore, in methods employing a rotatable wheel, the optical fiber is supplied and wired by placing tension on the optical fiber between the rotatable wheel and the reel, so that when sufficient friction cannot be obtained as described above, sufficient tension cannot be obtained, and this makes it impossible to rotate the rotatable wheel in such a manner as to feed only that length of optical fiber which is provided for in the pattern. As a result, this presents a drawback, as it is impossible to achieve the wiring of the pattern.
In conventional wiring methods which employ rotatable wheels in this manner, a number of drawbacks are present, such as the fact that a previously wired optical fiber pattern may become disordered as a result of the rotatable wheel at portions of the wiring pattern which are curved, the precision of the curving pattern cannot be improved as a result of limitations in the miniaturization of the rotatable wheel, and the fact that wiring cannot be conducted as provided for in the pattern when the pattern is such that wiring must conducted over previously wired optical fibers. These present problems when the length of the optical fibers must be made standard or when internal board wiring requires an extremely detailed pattern.
On the other hand, the through hole disclosed in Japanese Patent Application No. HEI 9-281645, which adopts a wiring head mechanism and does not employ a rotatable wheel, does have a simple mechanism; however, because the optical fiber inserted into the through hole is bent at the edge portion of the through hole, the central axis of the through hole and the position at which the optical fiber is applied to the substrate are not in agreement, and the optical fiber is wired at a position which is displaced by a corresponding amount from the track of the wiring head. In the same way as the conventional technology described above, this problem is magnified in the case of so-called multiple wiring, in which the wiring of the pattern employs curves or in which wiring must be conducted over previously wired optical fibers. A method has been considered as a countermeasure to this problem in which the displacement is anticipated in advance and the movement of the wiring head is corrected; however, the mechanism becomes complex, and furthermore, in cases in whi
Arishima Koichi
Hirayama Mamoru
Nakagawa Chikao
Sasaki Masayuki
Tamagaki Tsuneo
Kang Juliana K.
Nippon Telegraph & Telephone Corporation
Sanghavi Hemang
Thelen Reid & Priest LLP
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