subject: description of fusion splicer [print this page] description of fusion splicer description of fusion splicer
With increases in optical fiber cable density in recent years, the number of cores in ribbon-type optical fibers has been progressively increased and ribbon-type optical fibers, such as 16-core or 24-core optical fibers, have been progressivelyput to practical use. In order to collectively or in one operation fusion-splice the cores in such multi-core ribbon-type optical fibers by electric discharge, it is necessary to set the distance between the electric discharge electrodes large.
However, in the above-described fusion-splicing technique disclosed in Literature 1, when the distance between the electric discharge electrodes is set large, the middle portion of the path of electric discharge generated between theelectric-discharge electrodes is attracted upward, causing the path to be curved into a bow shape. FIG. 10 is a view illustrating a heat intensity distribution around the electric discharge electrodes according to the prior art fusion-splicingtechnique. This phenomenon is caused mainly by ascending airflows, which result from ambient air heated by electric discharge. Ascending airflows are generated in the direction of the arrow illustrated in FIG. 10, and these ascending airflows cause themiddle portion of the electric discharge path to be curved in the direction of the arrow. This results in, for example, the heat intensity distribution between the electric discharge electrodes, as illustrated in FIG. 10. Thus, the end portions ofoutermost optical fibers 3 (optical fibers proximal to the electric discharge electrodes 4) and optical fibers 3 positioned around the central zone would be heated to higher temperatures than the end portions of the other optical fibers 3. As a result,the end portions of optical fibers would have varying melting amount of fused portions, which prevents all the optical fibers 3 from being collectively or in one operation successfully fusion-spliced.
Therefore, it is an object of the present invention to provide optical fiber fusion splicer which can successfully fusion-splice together the end portions of optical fibers by electric discharge, regardless of the distance between the electricdischarge electrodes.
In order to achieve the above-described object, the optical fiber fusion splicer according to the present invention comprises (a) a pair of electric discharge electrodes provided opposed to each other along a predetermined axis; (b) a conductorelectrode disposed on one side with respect to a plane with the predetermined axis contained therein; and (c) means for generating electrostatic attraction in the direction tending from the plane toward the one side, between the conductor electrode andthe electric discharge path generated between the electric discharge electrodes, the means for generating electrostatic attraction being connected to the conductor electrode; (d) wherein end portions of optical fibers disposed on the other side withrespect to the above-described plane are fusion-spliced together by the electric discharge produced between the electric discharge electrodes.
In this optical fiber fusion splicer, when electric discharge is generated between the opposed electric discharge electrodes, electrostatic attraction is generated between the path of electric discharge (hereinafter, referred to as "electricdischarge path") and the conductor electrode disposed on the lower side with respect to the predetermined axis which extends between the electric discharge electrodes, namely, on the one side with respect to the plane including the predetermined axis. This electrostatic attraction attracts the electric discharge path towards the conductor electrode side (namely, towards the one side with respect to the above-described plane). Thus, the middle portion of the electric discharge path is prevented frombeing attracted upward by ambient air convection whereupon the electric discharge path to be curved into a bow-shape. Thus, the optical fiber fusion splicer according to the present invention is capable of fusion-splicing the end portions of opticalfibers to each other successfully, regardless of the distance between the electric discharge electrodes. This optical fiber fusion splicer is extremely effective, for example, in the case where the distance between the electric-discharge electrodes mustbe set large for collectively or in one operation fusion-splicing the respective cores of multi-core ribbon-type optical fibers. The electric-discharge path refers to the path of electrons or ionized gases, etc. resulting from electric dischargegenerated between the electric-discharge electrodes and is attributed to positive column, for example. Also, the electrostatic attraction refers to coulomb attraction, or attraction generated in accordance with Coulomb's law, being effectively activebetween areas charged with opposite polarities by electrostatic induction.
Preferably, the means for generating electrostatic attraction includes an electrical grounding portion. By connecting the electrical grounding section, grounded to the ground, to the conductor electrode, means for generating electrostaticattraction can simply constructed.
Preferably, the means for generating electrostatic attraction further includes a capacitive element connected between the conductor electrode and the electrical grounding portion. By disposing the capacitive element, such as a condenser, betweenthe conductor electrode and the electrical grounding portion, the amount of electrostatic attraction, which is generated between the electric-discharge path and the conductor electrode, can be controlled. Thus, it becomes possible to accomplish asuitable amount of electrostatic attraction acting on the electric-discharge path.
Preferably, the capacitive element is an element the capacitance of which is variable. Thus, the amount of electrostatic attraction, which is generated between the electric-discharge path and the conductor electrode can be continuously varied,so that it is made possible to control the amount by which the electrostatic attraction attracts the electric-discharge path, corresponding to the circumstances.
The optical fiber fusion splicer according to the present invention may include at least one pair of the conductor electrodes, which are opposed to each other in a direction substantially orthogonal to the predetermined axis. In this case, themeans for generating electrostatic attraction preferably includes capacitive elements the capacitances of which are variable, and a first capacitance control section for periodically varying the capacitance of each of the capacitive elements, whereineach of the capacitive elements is connected to a respective one of the conductor electrodes. Adopting this configuration makes it possible to periodically oscillate the electric discharge path between one conductor electrode side and the otherconductor electrode side, while preventing the middle portion of the electric-discharge path from being attracted upward. Namely, it becomes possible to scan the electric-discharge path along the longitudinal direction of optical fibers.
