JPH06279043A - Production of image fiber - Google Patents

Abstract

PURPOSE:To obtain image fibers improved in mechanical strength by uniting, under torsion at elevated temperatures, the primary matrix for image fibers with both the ends of bundled picture element fibers fixed into the secondary matrix followed by melt drawing from one end. CONSTITUTION:Firstly, many elemental optical fibers 2 are bundled and both of the ends are covered with quartz tubes 3 and fixed to make the primary matrix l for image fibers. Second, one end of this matrix 1 is fixed with a supporting member 4, the other end is ensured to revolve around the axis. In this mode, the matrix 1 is threaded into a core tube 6 which is maintained at high temperatures by injecting electric current into a cylindrical exothermic element 5 along with feeding an inert gas such as He via a feed port 7 into the core tube. Third, the exothermic element 5 is slowly moved toward the upper part of the core tube 6; concurrently, the other end of the primary matrix 1 is slowly revolved around the axis and united in a molten state under torsion into the secondary matrix for image fibers. Finally, the surface of the secondary matrix is put to fire polishing with a flame followed by drawing from one end of the matrix, thus affording the objective bubble-free, high-strength image fibers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method of manufacturing an image fiber used for medical purposes, and has a small diameter and high strength.

[0002]

2. Description of the Related Art A typical method for producing an image fiber is to first produce an optical fiber preform which is a source of a pixel, draw it once to make a fiber, and then cut it into a fixed length to make an image fiber strand. In this case, a large number of this standard length image fiber element wires are packed in a jacket tube to form an image fiber base material. This image fiber base material is melt-drawn from one end and a coating such as UV resin is applied on this image fiber. It is a winding method.

[0003]

However, in such a method, bubbles may be generated during drawing, and the image fiber containing bubbles has a problem of low strength. It is considered that the degree of bubble formation is almost proportional to the temperature during drawing, so if the temperature during drawing is lowered, the frequency of bubbles will decrease, but foreign matter on the surface of the jacket pipe may be blown off or scratched. It became impossible to smooth without eliminating the loss of strength of the image fiber. Further, since the jacket portion is present, it is difficult to say that the obtained image fiber has a small diameter.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to provide a method of manufacturing an image fiber in which the presence of bubbles is reduced from the above viewpoints. The primary preforms for image fibers obtained by bundling the pixel strands of the above, and fixing both ends of the bundle, are integrated into a secondary preform for image fibers by twisting at high temperature. It is to draw the melting line from one end. Further, the invention according to claim 2 is characterized in that one end of the primary preform for image fiber is fixed and the other end is rotated and twisted. When integrating the secondary base material for image fiber at high temperature, if the high temperature part is moved relatively in the length direction of the secondary base material for image fiber, it will move in the length direction of the base material. Since they are integrated in order, bubbles will not be trapped in the base material and will not become bubbles. In addition, if the base material is integrated and fire-polished with a flame as usual, dust and scratches on the surface of the base material can be removed, and the decrease in strength of the image fiber can be suppressed.

[0005]

[Function] A large number of fiber strands are bundled together and both ends thereof are fixed to form a primary base material for an image fiber. The primary base material is twisted and integrated at a high temperature, so that bubbles existing inside are extruded. Since it goes out and does not remain in the base material, the image fiber obtained from this base material has high strength with few bubbles. Further, since there is no jacket portion, the image fiber has a small diameter.

[0006]

EXAMPLE 1 FIG. 1 is a schematic explanatory view showing a method for obtaining a secondary base material for an image fiber according to the present invention. First, the structure thereof will be described. 1 is a primary base material for an image fiber and a large number of optical fiber elements. It is a bundle of wires 2,
A quartz tube 3 is covered only on both ends of the fiber tube to fix the bundled fiber element wires 2. Then, one end of the quartz tube 3 is supported and fixed to a support member described later, and the other end is slowly twisted around its axis by a rotating means (not shown). Reference numeral 4 denotes a support member for fixing one end of the primary base material 1 so that it does not move. Reference numeral 5 denotes a cylindrical resistance heating element arranged outside the primary base material 1 to be in a high temperature state by energization. Traverses the length of the. Reference numeral 6 is a core tube which is located inside the cylindrical heating element 5 and uniformly heats the primary base material 1. Reference numeral 7 is a supply port for feeding an inert gas such as He or N ₂ into the core tube 6. In the above structure, the primary base material 1 was placed in the core tube 6. The heating element 5 was energized to maintain the core tube 6 at a high temperature, and at that time, He gas was supplied into the core tube 6 through the supply port 7. While slowly traversing the heating element 5 toward the upper side of the core tube 6, the support member 4 for the primary base material 1
The upper end opposite to the lower end fixed by was slowly rotated by the rotating means. In this way, while heating the primary base material 1 to the softening temperature by the radiant heat of the core tube 6 and twisting the other end with one end fixed, the primary base material 1 is sequentially rotated from the fixed end side while being twisted. The secondary base material is melted and integrated toward the end side. At this time, the air existing between the optical fiber strands is pushed toward the rotating upper end portion of the primary base material 1, so that the obtained secondary base material does not contain bubbles inside. Becomes

[0007]

SPECIFIC EXAMPLE 1 A base material for a pixel having a core of Ge dove quartz and a clad of F-doped quartz was prepared. that time,
The relative refractive index difference between the core and pure quartz was 3%, and the relative refractive index difference between the cladding and pure quartz was -1%. That is, the relative refractive index difference between the core and the clad is 4%. Also,
The outer diameter was 40 mmφ and the length was 600 mm. This base material was first drawn into an optical fiber element wire having an outer diameter of 425 μm, the obtained optical fiber element wire was cut into a length of 500 mm, and a total of 6000 pieces were collected and bundled. Then, both ends of the bundled optical fiber strands are covered and fixed by 50 mm with a quartz tube having an outer diameter of 40 mmφ and an inner diameter of 36 mmφ so that the bundled 6000 optical fiber strands are not separated from each other to form a primary base material. did. One end of this primary base material was fixed to a support member, and the other end thereof was placed in the core tube while being rotatable about its axis. In this state, the heating element was energized to heat the primary base material to 1600 ° C. and He gas was fed into the core tube. Then, the heating element is moved upward from below the primary base material at a speed of 1 mm / min, and the other end of the primary base material is moved around the axis by 1
It was slowly rotated at a speed of rpm and melted and integrated to obtain a secondary base material. Next, the surface of the secondary base material was fire-polished with an oxyhydrogen flame, and then drawn from one end to form an image fiber having an outer diameter of 270 μm, which was coated with UV resin to have an outer diameter of 350 μm. The generation frequency of bubbles in this image fiber was one per 100 m, and when the fiber was subjected to a 360-degree bending test with a diameter of 15 mmφ, the rate of breakage was once per 100 m. By the way, in the case of the image fiber by the conventional method, the bubble generation frequency was 5 per 100 m, and the rate of breakage in the bending test was 5 per 100 m.
Further, the outer diameter of the fiber is 270 μm as described above, and 300 μm in the case of the conventional jacket.
Therefore, the diameter can be reduced by 10%.

[0008]

According to the method of manufacturing an image fiber according to the present invention, the image fiber element wires, which are to be a large number of pixels, are bundled and fixed only at both ends thereof to form a primary preform for the image fiber, which is twisted at a high temperature. It is a method of melt-integrating to obtain a secondary base material for an image fiber that does not contain bubbles, and melt-drawing this secondary base material from one end, so the obtained image fiber has a small diameter and high strength without bubbles. Becomes

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a method of the present invention.

[Explanation of symbols]

 1 Primary Base Material 2 Optical Fiber Element 3 Quartz Tube 4 Support Member 5 Heating Element 6 Core Tube 7 He Gas Supply Port

Front Page Continuation (72) Inventor Koji Tamanuma 1440 Rokuzaki, Sakura-shi, Chiba Fujikura Co., Ltd. Sakura Factory (72) Inventor Kazuo Sanada 1440 Rokuzaki, Sakura-shi, Chiba Fujikura Sakura Co., Ltd.

Claims (2)

[Claims] 1. A primary base material for an image fiber obtained by bundling a large number of pixel element wires and fixing both ends thereof to form a secondary base material for an image fiber by twisting at a high temperature to integrate the primary base material. A method for manufacturing an image fiber, which comprises melting and drawing a secondary base material from one end. 2. The method for producing an image fiber according to claim 1, wherein one end of the primary base material for an image fiber is fixed and the other end is rotated and twisted.