JP2011095507A - Method for manufacturing image fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an image fiber by which a high-quality image fiber is manufactured while restraining air bubbles from being produced to the utmost by improving inserting property of a pixel fiber into a glass tube. <P>SOLUTION: The image fiber 1 is manufactured by inserting and arranging a plurality of pixel fibers 3 comprising a glass fiber inside the glass tube 11, and heating the glass tube 11 together with the pixel fibers 3, to produce an image fiber base material 31 formed integrally with the glass tube 11 and the pixel fibers 3, and then heating, melting, and drawing one end of the image fiber base material 31. A glass tube whose variation width of an inside diameter is twice or less as large as an average diameter of the pixel fiber 3 is used as the glass tube 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an image fiber used for medical use or industrial use.

  Image fibers are used for medical purposes and industrial purposes, for example, for observation in narrow spaces in body cavities such as blood vessels and urinary organs, or for monitoring in adverse environments such as in a high-temperature furnace. The image fiber is obtained by bundling a plurality of pixel fibers and fusing them together to disassemble the image formed on the end face of the image fiber into each pixel fiber and transmitting it to the other end. As a technique for manufacturing such an image fiber, a quartz tube in which a silica-based optical fiber that becomes a large number of pixels is packed is etched in advance using hydrofluoric acid to remove scratches on the inner surface to obtain a smooth surface. An optical fiber is packed in a quartz tube thus obtained to form a base material, and an optical fiber is drawn from one end to form an image fiber (see, for example, Patent Document 1).

JP-A-7-33461

  Even if the inside of the quartz tube is etched as described above, when the pixel fiber, which is an optical fiber, is inserted into the quartz tube, the pixel fiber may be supported and the insertion work may be delayed. In such a case, the arrangement of the pixel fibers in the quartz tube may be disturbed, and bubbles may be scattered in a collapse process or a drawing process in which the optical fiber strands are heated and integrated after being sealed. Moreover, even if the pixel fiber is inserted and arranged well, bubbles may be generated.

  An object of the present invention is to provide an image fiber manufacturing method capable of improving the insertion property of a pixel fiber into a glass tube and manufacturing a high-quality image fiber while suppressing the generation of bubbles as much as possible.

In the method of manufacturing an image fiber according to the present invention that can solve the above-described problem, a plurality of pixel fibers made of glass fibers are inserted and arranged in a glass tube, and the glass tube is heated together with the pixel fibers to An image fiber manufacturing method for manufacturing an image fiber by manufacturing an image fiber preform in which a glass tube and the pixel fiber are integrated, and heating and drawing one end of the image fiber preform,
As the glass tube, a glass tube having a variation width of an inner diameter that is not more than twice an average diameter of the pixel fiber is used.

  In the image fiber manufacturing method of the present invention, it is preferable to use a glass tube whose inner diameter is monotonously changed in the longitudinal direction.

  In the image fiber manufacturing method of the present invention, it is preferable to use a glass tube having an uneven thickness that is not more than twice the average diameter of the pixel fiber.

  In the image fiber manufacturing method of the present invention, the glass tube preferably has an inner peripheral surface with a surface roughness of 1 μm or less.

  According to the image fiber manufacturing method of the present invention, by using a glass tube with a small variation width of the inner diameter, it is not supported when the pixel fiber is inserted, and the insertion property of the pixel fiber can be greatly improved. In addition, the collapse of the space in the glass tube due to fluctuations in the inner diameter of the glass tube can be eliminated during the collapsing process that is heated and integrated after the pixel fiber is sealed to form an image fiber base material. It is possible to manufacture a high-quality image fiber in which generation is suppressed as much as possible.

It is sectional drawing of the image fiber which shows the structure of an image fiber. It is a perspective view of the glass tube used for the manufacturing method of the image fiber concerning this embodiment. It is a perspective view of the glass tube in which a pixel fiber is inserted in the manufacturing method of the image fiber which concerns on this embodiment. It is a schematic diagram which shows the collapse process of the manufacturing method of the image fiber which concerns on this embodiment. It is a perspective view of an image fiber preform showing a manufacturing method of an image fiber concerning this embodiment. It is a schematic diagram which shows the drawing process which shows the manufacturing method of the image fiber which concerns on this embodiment. It is a figure which shows the space formed between a glass tube and pixel fiber, and is a schematic diagram of the glass tube in which the pixel fiber was accommodated.

Hereinafter, an example of an embodiment of a method for manufacturing an image fiber according to the present invention will be described with reference to the drawings.
As shown in FIG. 1, the image fiber 1 is manufactured by drawing an image fiber preform 31 to be described later, and a plurality of (several thousand to several tens of thousands) are provided inside a quartz jacket 2. The pixel fiber 3 is disposed, and a jacket 4 is provided on the outer periphery of the jacket 2. The coating 4 is made of a thermosetting resin such as polyimide resin or silicon resin, or an ultraviolet curable resin.

Each of the pixel fibers 3 is a glass fiber having a core and a clad, and forms an independent optical line.
One end of the image fiber 1 is an eyepiece side, the other end is an object side, and light incident on the end face of the object side pixel fiber 3 is emitted from the end face of the eyepiece side pixel fiber 3. These pixels can be observed on the eyepiece side.

Next, a method for manufacturing the image fiber 1 will be described.
First, an image fiber preform is produced. In order to fabricate the image fiber preform, a glass tube 11 serving as the jacket 2 is prepared as shown in FIG.
In order to manufacture the glass tube 11, for example, a glass base material is manufactured by a VAD method (Vapor phase Axial Deposition method) in which an oxyhydrogen flame is blown onto a glass rod by a burner to deposit glass particles on the glass rod. And a hole is formed in the center axis | shaft of this glass base material, and also an internal pressure is provided in a hole in the state softened by heating, and diameter expansion is carried out.

Next, the outer diameter D, the wall thickness T, and the surface roughness Ra of the inner peripheral surface are measured for the glass tube 11 thus manufactured.
The outer diameter D is measured using a laser outer diameter measuring device, the wall thickness T is measured using a laser displacement meter, and the surface roughness Ra of the inner peripheral surface is measured using an optical interferometer.
The measurement of the outer diameter D and the wall thickness T is performed at a plurality of locations in the circumferential direction of the glass tube 11. For example, the measurement is performed at 45 ° intervals in the circumferential direction of the glass tube 11. And this measurement is each performed in the some place which opened the predetermined space | interval in the longitudinal direction of the glass tube 11. FIG.
For example, when the standard dimensions of the glass tube 11 are an outer diameter D = 30 mm, a wall thickness T = 1.5 mm, and a length L = 300 mm, the glass tube 11 is spaced apart by 20 mm in the longitudinal direction. Measure at a point.

  Then, the inner diameter d of the glass tube 11 is obtained by subtracting the thickness T from the outer diameter D, and the uneven thickness of the glass tube 11 is obtained from the thickness T. In addition, the thickness deviation uses the largest thickness difference among the four sets of thickness values which are symmetrical with respect to the central axis and face each other.

  As a result of the measurement, the glass tube 11 in which the fluctuation range of the inner diameter d in the longitudinal direction of the glass tube 11 (difference between the maximum value and the minimum value of the inner diameter) is not more than twice the average diameter of the pixel fibers 3 is used. For example, when the average diameter of the pixel fiber 3 is 200 μm, a glass tube 11 having a variation width of the inner diameter d of 0.4 mm or less is used.

  Moreover, it is preferable to use the glass tube 11 in which the thickness deviation in the longitudinal direction of the glass tube 11 is not more than twice the average diameter of the pixel fibers 3. For example, when the average diameter of the pixel fiber 3 is 200 μm, the glass tube 11 having an inner diameter d with a thickness deviation of 0.4 mm or less is used.

  Moreover, it is preferable to use the glass tube 11 whose change of the internal diameter d of the glass tube 11 is monotonous in the longitudinal direction. The monotonous change refers to a state in which the inner diameter d gradually increases or decreases from one end side to the other end side of the glass tube 11.

  Moreover, it is preferable to use the glass tube 11 whose surface roughness Ra of the inner peripheral surface of the glass tube 11 is 1 μm or less.

  Then, the glass tube 11 satisfying the above conditions is ultrasonically cleaned with ultrapure water, and a predetermined number of pixel fibers 3 are inserted and accommodated as shown in FIG. In the glass tube 11 whose standard dimensions are an outer diameter D = 30 mm, a wall thickness T = 1.5 mm, and a length L = 300 mm, about 16000 pixel fibers 3 having an average diameter of 200 μm (200 μm ± 24 μm) are inserted.

The glass tube 11 in which the pixel fiber 3 is inserted and accommodated is sufficiently dried in dry air, and further heated while introducing chlorine gas to remove residual moisture and impurities.
Thereafter, as shown in FIG. 4, the glass tube 11 containing the pixel fiber 3 is traversed by a burner 21 in the axial direction, and the glass tube 11 is collapsed by being heated and melted by an oxyhydrogen flame from the burner 21. Then, the diameter of the glass tube 11 is reduced to obtain an image fiber preform 31 in which a plurality of pixel fibers 3 and the glass tube 11 are integrated as shown in FIG. In this collapse step, the collapse temperature is about 1900 ° C., and the collapse speed, which is the traverse speed, is about 5 mm / min.

  As shown in FIG. 6, the image fiber preform 31 manufactured as described above is placed in the heating furnace 22 from one end side thereof, and one end of the image fiber preform 31 is heated and melted to draw, A coating 4 is formed by applying a resin to the outer periphery. This drawing step is performed at a drawing temperature of about 2100 ° C. and a drawing speed of about 30 m / min.

  If the fluctuation width of the inner diameter d of the glass tube 11 is large (for example, an inner diameter fluctuation of 0.5 mm or more), when the pixel fiber 3 is inserted into the glass tube 11, the pixel fiber 3 may support and insertion work may be delayed. In such a case, the arrangement of the pixel fibers 3 in the glass tube 11 may be disturbed, and bubbles may be scattered in the collapse process or the drawing process. In addition, when the fluctuation range of the inner diameter d of the glass tube 11 is large, even when the pixel fiber 3 is inserted and arranged well, as shown in FIG. 7, the gap between the glass tube 11 and the bundle of pixel fibers 3 is as shown in FIG. A space S is formed, and after the collapse process, bubbles may be scattered due to the collapse of the space S.

  In the present embodiment, since the glass tube 11 with a small inner diameter variation in which the variation width of the inner diameter d is less than twice the average diameter of the pixel fiber 3 is used, it is difficult for the pixel fiber 3 to be supported and the pixel fiber 3 is inserted. The insertability can be greatly improved. Further, the collapse of the space S in the glass tube 11 caused by the fluctuation of the inner diameter d during the collapse process can be eliminated, and the high-quality image fiber 1 in which the generation of bubbles in the manufacturing process is suppressed as much as possible is manufactured. be able to.

Further, even when the inner diameter d of the glass tube 11 is randomly changed in the longitudinal direction or the thickness deviation of the glass tube 11 is large, bubbles may be scattered in the collapse process or the drawing process. In the present embodiment, the glass tube 11 in which the fluctuation of the inner diameter d is monotonously changed in the longitudinal direction is used, and the glass tube 11 whose deviation is less than twice the average diameter of the pixel fiber 3 is used. The generation of bubbles in can be further suppressed.
In addition, as the glass tube 11, since the inner peripheral surface has a surface roughness Ra of 1 μm or less and the inner peripheral surface is smooth, bubbles are also generated in the manufacturing process due to the inner peripheral surface roughness Ra. Can be suppressed.

  Image fiber preforms were produced using glass tubes having different shape characteristics, image fibers were drawn from the image fiber preform, and the bubble generation frequency per 100 m of each image fiber was measured and evaluated.

(Manufacture of image fiber)
A glass tube having standard dimensions of an outer diameter of 30 mm, a wall thickness of 1.5 mm and a length of 300 mm is ultrasonically cleaned with ultrapure water, and then about 16000 pixel fibers having an average diameter of 200 μm (200 μm ± 24 μm) are inserted. And housed.
The glass tube containing the pixel fiber is sufficiently dried in dry air, heated while introducing chlorine gas to remove residual moisture and impurities, and oxyhydrogen flame at a collapse temperature of about 1900 ° C and a collapse speed of about 5 mm / min. Was collapsed into an image fiber preform.
The produced image fiber preform was drawn at a drawing temperature of about 2100 ° C. and a drawing speed of about 30 m / min to produce an image fiber.

(Evaluation results)
The evaluation results are shown in Table 1. In addition, the bubble generation frequency made less than 3 favorable.

  As can be seen from Table 1, in Examples 1 to 5, in which the inner diameter variation of the glass tube is not more than twice (0.4 mm) the average diameter of the pixel fiber, it is preferable that the bubble generation frequency is less than three. all right. In particular, in Example 1, since the inner diameter variation was as small as 0.25 mm, even when the inner diameter variation pattern changed randomly in the longitudinal direction, the frequency of bubble generation was very small at 0.5. Further, in Example 3 in which the inner diameter variation is 0.4 mm, since the inner diameter variation pattern is monotonous in the longitudinal direction, the bubble generation frequency is 0.5 as in Example 1 in which the inner diameter variation is 0.25 mm. There were very few.

In Example 4, although the inner diameter variation pattern randomly changes in the longitudinal direction and the deviation amount is as large as 0.5 mm, the value of the inner diameter variation is small (below twice the average diameter of the pixel fiber). Bubble generation frequency was less than three. However, in Example 4, bubbles were unevenly distributed on one side in the circumferential direction.
In Example 5, although the inner diameter variation pattern randomly changes in the longitudinal direction and the surface roughness is as large as 1.8 μm, the inner diameter variation value is small (below twice the average diameter of the pixel fiber). Bubble generation frequency was less than three.

  On the other hand, in Comparative Examples 1 and 2 of 0.5 mm and 0.6 mm in which the inner diameter variation exceeds twice (0.4 mm) the average diameter of the pixel fiber of 200 μm, the bubble generation frequency is 3.8 and In Comparative Example 2 in which there were many, especially the inner diameter variation was 0.6 mm, the frequency of bubble generation was high even if the inner diameter variation was monotonous.

  1: Image fiber, 3: Pixel fiber, 11: Glass tube, 31: Image fiber base material

Claims (4)

A plurality of pixel fibers made of glass fiber are inserted and arranged inside a glass tube, and the glass tube is heated together with the pixel fiber to produce an image fiber preform in which the glass tube and the pixel fiber are integrated. An image fiber manufacturing method for manufacturing an image fiber by heating and drawing one end of the image fiber preform,
A method for producing an image fiber, wherein the glass tube has a variation width of an inner diameter that is not more than twice an average diameter of the pixel fiber. A method for producing an image fiber according to claim 1,
A method for producing an image fiber, wherein the glass tube has an inner diameter that changes monotonously in the longitudinal direction. An image fiber manufacturing method according to claim 1 or 2,
A method for producing an image fiber, wherein the glass tube has an uneven thickness that is equal to or less than twice the average diameter of the pixel fiber. An image fiber manufacturing method according to any one of claims 1 to 3,
An image fiber manufacturing method, wherein the glass tube has an inner peripheral surface with a surface roughness of 1 μm or less.

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