JPH111347A - Melt-spinning of optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems caused by feedbacking the data from the optical fiber outer diameter-measuring device in order to obtain naked optical fiber having a certain outer diameter, for example, on fluctuation of the optical fiber take-up speed, unevenness of the outer diameter of the coating layer, the degree of crosslinking and Young's modulus, moreover the fiber breakage due to leaving of the element fiber 14 from the pulley in the case that the fluctuation in the optical fiber taking-up speed is large. SOLUTION: The taking-up speed of the naked optical fiber 12 is kept constant and the data on the outer diameter measured on the optical naked fiber 12 are feedbacked to the feeding rate of the optical fiber parent material 10 thereby controlling the outer diameter of the naked optical fiber so that it may be kept constant. Thus, optical elementary fiber having a uniform coating layer all over the fiber length is obtained with no occurrence of trouble on the line winding-up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for spinning an optical fiber, and it is an object of the present invention to obtain an optical fiber having a long and uniform characteristic.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a conventional optical fiber spinning apparatus. Reference numeral 10 denotes an optical fiber preform, and reference numeral 20 denotes a feeding device, which includes, for example, a bracket 22 for supporting the optical fiber preform 10, a screw 24, a motor 26, and the like. 28 is a heating furnace, 30 is an outer diameter measuring device for the bare optical fiber 12, 32 is a resin coating device, 34 is a cross-linking device, 36 is an outer diameter measuring device for the optical fiber wire 14, 38 is a take-off machine, 40 is It is a winding machine.

Conventionally, in order to obtain the bare optical fiber 12 having a constant outer diameter, the following method has been used. That is,
The optical fiber preform 10 is sent out at a constant speed, and the measurement data of the outer diameter measuring device 30 is fed back to the take-off device 38,
When the outer diameter of the bare optical fiber 12 is larger than the target value, the take-up speed is increased, and when the outer diameter of the bare optical fiber 12 is small, the take-up speed is reduced.

[0004]

The above method has the advantage that the outer diameter of the bare optical fiber 12 is stabilized, but the following problems occur because the take-up speed fluctuates. As understood from the “relationship between the take-up speed and the outer diameter of the optical fiber 14” shown in FIG. 3, when the take-up speed changes, the outer diameter of the optical fiber 14 changes. Further, as understood from the “relationship between the take-up speed and the gel fraction (cross-linking degree)” shown in FIG. 4, when the take-up speed changes, the cross-linking degree changes in the length direction. Further, as understood from the “relationship between take-up speed and Young's modulus” shown in FIG. 5, when the take-up speed changes, the Young's modulus of the coating material changes in the length direction. Also, as understood from the “relation between the take-up speed and the surface tackiness” shown in FIG. 6, when the take-up speed changes,
The surface properties of the coating vary in the length direction.

If the change in the take-up speed is large, the winding state of the take-up device 40 is disturbed. FIG. 7 shows the relationship between the change in the take-up speed and the occurrence of winding failure. As will be understood from the above, when the take-up speed is constant, no winding failure occurs.

[0006]

According to the first aspect of the present invention, as shown in FIG. 1, the pulling speed of the bare optical fiber 12 is kept constant. By adjusting the sending speed of the optical fiber preform 10 based on the measured data of the outer diameter, the outer diameter of the bare optical fiber 12 is kept constant.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given with reference to FIG. As the apparatus for spinning, almost the same apparatus as the conventional apparatus shown in FIG. 2 is used. However, in order to make the outer diameter of the bare optical fiber 12 constant, the measurement result of the outer diameter measuring device 30 is fed back to the feeding device 20 of the preform 10.

When the outer diameter of the bare optical fiber 12 is larger than the target value, the feeding speed of the optical fiber preform 10 is reduced (the rotation speed of the screw 24 is reduced). Then, although the take-up speed does not change, the supply amount of the base material 10 decreases, so that the bare optical fiber becomes thin. Conversely, when the outer diameter of the optical fiber 14 is smaller than the target value, the feeding speed of the optical fiber preform 10 is increased. With the above automatic control, a bare optical fiber having a constant outer diameter can be obtained even if the take-up speed is constant.

[0009]

Since the take-off speed does not change, an optical fiber having uniform outer diameter, degree of crosslinking, Young's modulus, and surface properties of the coating can be obtained over the entire length. The occurrence of defects in winding can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a spinning method of the present invention.

FIG. 2 is an explanatory view of a conventional spinning method.

FIG. 3 is a diagram showing a relationship between a take-up speed and an outer diameter of an optical fiber.

FIG. 4 is a diagram showing a relationship between a take-off speed and a gel fraction (crosslinking degree) of a coating.

FIG. 5 is a diagram showing a relationship between a take-up speed and a Young's modulus of a coating.

FIG. 6 is a diagram showing the relationship between the take-off speed and the surface tackiness of the coating.

FIG. 7 is an explanatory diagram showing the relationship between the presence or absence of a change in the take-up speed and the occurrence of winding failure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical fiber preform 12 Optical fiber bare wire 14 Optical fiber strand 20 Feeding device 22 Bracket 24 Screw 26 Motor 28 Heating furnace 30 Outer diameter measuring device 32 Resin coating device 34 Cross-linking device 36 Outer diameter measuring device 38 Pulling machine 40 Rolls Picking machine

Claims (1)

[Claims] 1. An optical fiber spinning method comprising: continuously feeding out an optical fiber preform, heating and melting a tip portion in a heating furnace, drawing the optical fiber into a bare optical fiber, applying a coating, and then drawing the optical fiber. The take-off speed of the bare optical fiber is kept constant, and the feeding speed of the preform of the optical fiber is adjusted based on the measured data of the outer diameter of the bare optical fiber, so that the outside of the bare optical fiber is adjusted. A method for spinning an optical fiber, characterized in that the diameter is kept constant.