JPS6229761B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for finishing the end face of a plastic optical fiber, and an object thereof is to easily finish the end face of a plastic optical fiber, and to provide a plastic optical fiber that shrinks when cooled. To provide an end face finishing device that can easily finish a fiber end face into a flat surface.

Conventionally, this type of end face finishing apparatus has been used to finish an end face 1a of a plastic optical fiber 1 as shown in FIG.
The upper surface 2a of the molding jig 2 is pressed against the heated upper surface 2a of the molding jig 2 to heat-form the end surface 1a. 4 and a molded part 5 made of a glass plate attached at 4, and the upper surface 2a of the molded part 5
is a flat mirror surface. In the figure, reference numeral 6 denotes a chuck portion for chucking the optical fiber 1 to the guide ring 7, and by rotating the cap 8 clockwise, the optical fiber 1 is clamped and held by the grip portion 9. Reference numeral 10 denotes a deburring ring, the lower part of which is conical and the lower edge of the optical fiber insertion hole 10a is blade-shaped. When the optical fiber 1 comes into contact with the lower end periphery of the optical fiber insertion hole 10a, the burr formed on the periphery of the end face 1a of the optical fiber 1 is cut off. Reference numeral 11 denotes a cooling medium injection port, and the heat-formed part is forcibly cooled by the cooling medium such as air injected from this injection port 11. 12 is a forming jig 2
It is a vise that fixes the In addition, optical fiber 1
Optical fiber insertion hole 10 of deburring ring 10
It is set so that it slightly protrudes from the lower end periphery of a, and the amount of protrusion is adjusted using a spacer 13.

By the way, in such a conventional example, since the upper surface 2a of the forming jig 2 is a flat mirror surface,
The end surface 1a of the optical fiber 1 is formed into a flat surface when heated, as shown in FIG. 3a. However, when this heat-formed part is cooled, the center of the end surface 1a becomes depressed as shown in FIG. There was a problem that the end surface 1a became a concave curved surface. That is, in this type of end face finishing device, the end face 1a of the optical fiber 1 is heated while the optical fiber 1 is held by the deburring ring 10, so that the outer periphery of the end face 1a of the optical fiber 1 is heated. The heat dissipation at the outer edge becomes larger than that at the center, the rate of temperature rise (heating rate) around the edge becomes smaller than at the center, and the amount of thermal expansion at the outer edge becomes smaller than that at the center. ing. Therefore, if the end face 1a of the optical fiber 1 is heat-molded on a flat molding surface in such a thermally expanded state, the amount of contraction during cooling will be larger at the center than at the outer periphery. As shown in FIG. 4, the end surface 1a of No. 1 becomes a concave curved surface with a concave central portion (the amount of shrinkage is indicated by an arrow). In addition, the temperature drop rate (cooling rate) during the cooling process is faster at the outer circumference than at the center due to heat dissipation by the deburring ring 10, and solidification starts from the outer circumference and gradually progresses to the center. During the shrinkage process during cooling, the radial shrinkage of the heat-formed portion is suppressed and most of the shrinkage occurs in the axial direction, resulting in a larger amount of shrinkage in the central portion. Note that the burr formed on the end surface 1a of the optical fiber 1 during heat forming will be caught on the lower edge of the burring ring 10 until it is cut, so the outer periphery of the end surface 1a will be attached to the lower edge of the burring ring 10. Since it is stretched by the peripheral edge, radial contraction is further suppressed. As described above, in the conventional example, even though the end surface 1a is heat-formed into a flat surface, the end surface 1a becomes a concave curved surface after cooling, resulting in a problem that the connection loss of the optical fiber 1 increases. It was hot.

The present invention has been made in view of the above points.

Examples will be described below using figures. Figures 5 to 7 show an embodiment of the present invention, in which a deburring ring 10 is inserted into the end of a plastic optical fiber 1, and the end surface 1a of the optical fiber 1 protruding from the deburring ring 10 is heated. In an end face finishing apparatus similar to the conventional example in which the molding surface of the molding jig 2 is pressed until it abuts against the deburring ring 10 and the end face 1a is heated and formed, the molding part 5 of the molding jig 2 is The upper surface 2a is formed of a glass plate with a mirror-like molded surface consisting of a concave curved surface having an appropriate curvature, and the end surface 1a of the optical fiber 1 is molded into a convex curved surface that becomes a flat surface when cooled. It's becoming like that.

Now, FIG. 7a shows the end of the optical fiber 1 immediately after heat forming, and the end surface 1 in the heated state is shown in FIG.
a is a convex curved surface. When the heated molded part is forcibly cooled in such a state by the cooling medium injected from the injection port 11 as in the conventional example, shrinkage occurs by the same mechanism as in the conventional example, and the central part of the end surface 1a is moved to the peripheral part. It shrinks a lot in comparison. Therefore, the central part of the protruding end surface 1a is recessed and the seventh
As shown in FIG. b, a flat end surface 1a is obtained during cooling. In other words, the end surface 1a of the optical fiber 1 is formed into a convex curved surface in advance in consideration of the amount of shrinkage during cooling, thereby canceling the amount of shrinkage during cooling. For example, when the diameter of the optical fiber 1 is 1 mmφ and the heat forming temperature is 220 to 260°C, if the radius of curvature of the forming part 5 made of a concave curved surface of the forming jig 2 is set to 50 to 80 mm, the optical fiber 1
The end surface 1a becomes a flat surface during cooling.

As described above, in the present invention, the molding surface of the molding jig is made into a concave curved surface having an appropriate curvature, and the end surface of the optical fiber is molded into a convex curved surface that becomes a flat surface when cooled. The end face of the optical fiber can be finished by a simple operation of pressing the molding surface of a heated molding jig against the end face of the optical fiber, and the end face of the optical fiber, which shrinks during cooling, can be finished into a flat surface. This makes it possible to reduce the connection loss of optical fibers.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the conventional example, Figure 2 is a detailed view of the main parts of the same as above, Figures 3 a and b are explanatory diagrams of the same as above, and Figure 4
The figure shows the heat shrinkage mechanism of a plastic optical fiber, Figure 5 is a sectional view of one embodiment of the present invention, Figure 6 is a detailed view of the main parts of the same, and Figures 7 a and b are explanations of the operation of the same. It is a diagram. 1 is an optical fiber, 1a is an end face, 2 is a forming jig, and 15 is a cooling means.

Claims (1)

[Claims] 1. Insert a burring ring into the end of the plastic optical fiber, and press the molding surface of the heated molding jig against the end face of the optical fiber protruding from the burring ring until it abuts against the burring ring. In an end-face finishing device for heating and forming an optical fiber, the forming surface of the forming jig is formed into a concave curved surface with an appropriate curvature, and the end surface of the optical fiber is formed into a convex curved surface that becomes a flat surface when cooled. An end face finishing device for plastic optical fiber, which is characterized by: