JPS6260681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an optical fiber sheet in which a large number of optical fibers are arranged at regular intervals.

Optical fibers are roughly divided into two types depending on their purpose: those used for transmitting optical signals, and those used for transmitting sensors or images. For the former purpose of optical signal transmission, there is no problem in using the optical fiber as a single fiber, a sheet-like material with irregularly arranged single fibers, or a focused fiber bundle, but for the latter purpose, for use in transmitting a sensor or an image. For this purpose, the single fiber positions on the input side and output side must be arranged so that they correspond to each other, and the distance between the single fibers must be as close as possible, and unless the sheet-like object or fiber bundle is regularly arranged, the detection position on the input side will be on the output side. Therefore, when used for image transfer, the image on the exit side will appear distorted, so several methods have been proposed to arrange the single fibers regularly. Various problems arose.

Conventionally, methods for manufacturing optical fiber sheets in which individual single fibers are regularly arranged include: (1) After winding up each individual single fiber in order on the circumference of a drum or skein frame and fixing a portion with adhesive; (2) A method in which grooves are formed at regular intervals on the circumference of a drum or skein frame, the single fibers are lined up along the grooves and wound up, and a portion is cut in the middle of the bonded part. There is a method of manufacturing a sheet-like article by fixing with adhesive and then cutting in the middle of the adhesive part. However, optical fibers usually have unevenness of ±5 to 10% in single fiber diameter. Therefore, in the method (1) above, if the single fibers are wound in contact with each other, it is difficult to arrange the single fibers regularly due to unevenness in the diameter of the single fibers, much less to arrange them at regular intervals. This is extremely difficult considering that the fiber cross section is circular. In addition, in the method (2) above, when the single fiber diameters are relatively thick and the intervals are wide, it is possible to arrange each single fiber regularly, but when the single fiber diameters are thin and the intervals are narrow, it is possible to arrange each single fiber regularly. The mechanical precision of groove machining is a problem, and it is also very difficult to manufacture large diameter drums and skeins.
Furthermore, in all of the above cases, continuous processing is impossible because the production is done in batches, and furthermore, it is necessary to prepare different drums and skeins depending on the required sheet length and fiber spacing. There is.

In order to solve the above-mentioned drawbacks, the present inventors investigated various methods and found that it is possible to continuously produce optical fiber sheets by using a film that contracts only in the direction perpendicular to the fiber axis. We have arrived at the present invention. That is, in the present invention, optical fibers are arranged on a plane with regular intervals, and heat-shrinkable films that contract only in the direction perpendicular to the axis of the fiber group are placed on both sides of the aligned optical fiber group. This is a method for producing an optical fiber sheet material, which comprises fixing the fibers entirely or partially to the fibers and then heat-treating the fibers to shrink the distance between each fiber of the fiber group to a predetermined distance.

The optical fibers used in the present invention can be either glass-based or synthetic resin-based, but synthetic resin-based optical fibers are particularly preferred because they have excellent flexibility. Each optical fiber used has a diameter of 0.05 mm to 5 mm.

Further, in the present invention, the heat-shrinkable film is produced by uniaxial stretching so that it shrinks only in the direction perpendicular to the axis of the aligned optical fiber group.
Moreover, a material having adhesiveness on only one side is used. This heat-shrinkable film is preferably fixed to both sides of the optical fiber group to form a sandwich structure in which the optical fiber group is sandwiched between the heat-shrinkable films. The heat-shrinkable film may be continuously supplied along with the optical fiber group and fixed to the optical fiber group, but the heat-shrinkable film may also be supplied intermittently in the length direction and partially fixed.

In the present invention, each optical fiber is a filament thread wound around a bobbin, which is pulled together at a constant speed, and then taken off at a constant speed through a heat treatment process while supplying a heat shrink film, to form a continuous sheet. can get things.

Hereinafter, the method of the present invention will be specifically explained with reference to the drawings.

In FIG. 1, an optical fiber (1) is applied with a constant tension from a bobbin 2 of a creel stand, and is sent to a heat-shrinkable film fixing part by a yarn feeding roller 3. The heat shrink film fixing section includes a groove guide 4 having grooves at regular intervals, a supply bobbin 6 around which the heat shrink film 5 is wound, a pair of film supply rollers 7 that supply the heat shrink film 5 with a constant tension, and a constant pressure. It consists of a pair of nip rollers 8 which nip the optical fiber 1 and the heat shrink film 5 together. Further, when the optical fiber 1 and the heat-shrinkable film 5 are partially bonded, a device having a built-in cutter is required to feed the heat-shrinkable film 5 to the nip roller pair 8 intermittently.

The optical fibers 1 fed by the yarn feeding roller 3 are regularly arranged in the groove guide 4, and then placed in a sandwich structure with the heat-shrinkable film 5 fed from the feeding bobbin 6 by the film feeding roller pair 7, by the nip roller pair 8. It is fixed by Next, the first delivery roller 9 sends the fixed fiber sheet with the sandwich structure to the heat chamber 10, and shrinks the fiber sheet with the sandwich structure, thereby shrinking each optical fiber at a predetermined rate. After being made into a shape, it is cooled by a second delivery roller 11 consisting of a water-cooled roller, taken up at the same time, and wound up in a winder 12.

FIG. 2 shows a state in which the optical fibers 1 in FIG. 1 are arranged at regular intervals by the groove guide 4 and then fixed to the heat shrink film 5 and the sandwich structure in a cross-sectional view in a direction perpendicular to the fibers. It is something.

FIG. 3 is a cross-sectional view taken in a direction perpendicular to the optical fibers 1, showing a state in which the spacing between the optical fibers 1 is contracted at a predetermined rate by the heat chamber 10.

As explained above, by using the method of the present invention, it is possible to continuously produce optical fiber sheets in which the fibers are arranged in a very regular manner with a small spacing between the fibers. It is also possible to easily adjust the fiber spacing arbitrarily by adjusting the heat chamber temperature, etc., and the optical fiber sheet produced by this method can be used as a sheet or laminated as a fiber bundle for high-precision sensors, Furthermore, it has the advantage that it can be used in fiberscopes and the like used for transferring images, and can be cut to any desired length.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of a manufacturing apparatus for carrying out the present invention, FIG. 2 is a cross-sectional view of an optical fiber sheet in which optical fibers and a heat shrink film are fixed to a sandwich structure, and FIG. The figure shows a cross-sectional view of the optical fiber sheet after heat shrinkage.

Claims (1)

[Claims] 1 Optical fibers are arranged on a plane with regular intervals, and a heat-shrinkable film that shrinks only in the direction perpendicular to the axis of the fiber group is applied to the entire surface or on both sides of the optical fiber group. 1. A method for producing an optical fiber sheet, which comprises partially fixing the fibers and then heating the fibers to shrink the distance between the fibers to a predetermined distance.