JPS6135406A - Ferrule for optical connector - Google Patents

Abstract

PURPOSE:To obtain freely length enough to fix a bare optical fiber to the ferrule and also to polish the tip of the ferrule smoothly by making at least the inner peripheral side of the bare optical fiber insertion hole of a glass body which has an internal hole nearly as large as a bare optical fiber. CONSTITUTION:One terminal of a glass pipe 4 which has specific length and has its internal diameter nearly equal to that of the bare optical fiber F is inserted and fixed temporarily in the holding hole 12A of a lower mold 10A and an upper mold 10B is placed; and the lower mold 10A and lower mold 10B are fixed in one body with an unshown bolt. Then, a core pin 14 engaged threadably with the upper mold 10B is rotated in a downward direction to hold the upper end of the glass pipe 4 with its tip and arranging the glass pipe 4 and core pin 14 in mold hollows 11A and 11B linearly. In this state, plastic is injected into an injection hole 15 to mold the ferrule body, and the core pin 14 is extracted and the tip of the glass pipe 4 at the tip part of the ferrule body is cut in the same plane with the end surface of the ferrule body, manufacturing the ferrule body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a ferrule for a plastic optical connector used when connecting optical fibers.

(Prior art) A ferrule for an optical connector has an insertion hole for an optical fiber in the center, the tip of the insertion hole is the bare optical fiber with the coating removed, and the rear end is the part of the coated optical fiber. This is the insertion hole for the part.

By the way, recently, due to advances in plastic molding technology, plastics that are cheap and can be manufactured in large quantities have come to be used as ferrules for multi-optical connectors.

(Problems to be Solved by the Invention) However, there are the following problems when molding a ferrule for an optical connector using a plastic mold.

That is, since the outer diameter of the bare optical fiber inserted into the tip of the ferrule is, for example, about 125 μm, the outer diameter of the core pin for molding is also about 125 μm at the portion into which the bare optical fiber is inserted. For this reason, the pin axis may become eccentric due to the injection pressure of the resin during molding, and the core pin may be damaged in some cases. Therefore, the length of the tip of the core pin, that is, the pin into which the bare optical fiber is inserted, can be only about 1 inch long at most. Therefore, there are disadvantages such as there being a small adhesive area for fixing the bare optical fiber and the ferrule, and the tip of the ferrule into which the bare optical fiber is inserted cannot be polished long enough to make it smooth.

Furthermore, if the bare optical fiber insertion hole of the ferrule is made of plastic, the bare optical fiber inserted and fixed into the insertion hole and the plastic have different coefficients of thermal expansion, so if used for a long period of time, the bare optical fiber will leak from the tip of the ferrule due to heat cycles. There is a problem with the fiber sticking out.

(Means for Solving the Problems) In order to solve the above problems, the ferrule for optical connectors of the present invention has a bare optical fiber insertion hole and a coated optical fiber insertion hole communicating with the insertion hole. ,
The bare optical fiber insertion hole is characterized in that at least its inner peripheral side is made of a glass body having an inner hole of the same size as the bare optical fiber.

(Example) Hereinafter, an example of the ferrule for an optical connector of the present invention will be described in detail with reference to the drawings.

In FIGS. 1('r) and 1(b), 1 is the ferrule body. The ferrule body l has an insertion hole 2 for a bare optical fiber F made of quartz glass as shown in the figure on the front end side of the central axis, and an insertion hole 2 for a coated optical fiber C with a larger diameter on the rear end side. The hole is provided in communication with the insertion hole 2. A glass pipe 4 having a coefficient of thermal expansion approximately equal to that of the bare optical fiber F is provided at least on the inner circumference side of the insertion hole 2 on the tip side, and the outer circumference and rear end side of the glass pipe are made of plastic. 5, the plastic 5 is formed integrally with a glass pipe by molding. In this case, if a glass pipe with an uneven surface is used, the glass pipe 4 and the plastic 5 will be even more firmly attached. In FIGS. 1(A) and 1(B), 6 is a flange and is a positioning stopper when the ferrule main body 1 is inserted into an adapter (not shown).

Such a ferrule for an optical connector is manufactured using a mold described below.

In FIG. 2, 10 is a mold, 10A is a lower mold, and 10B is an upper mold. The lower mold 10A has a mold
A holding hole 12A into which one end of a glass pipe is inserted is provided at the bottom 12 at the tip of the pipe 11A. The upper mold IQB is provided with a screw hole 13, and this screw hole 13 is connected to the lower mold 1.
The axis coincides with the holding hole 12A provided at 0A. A core pin 1i, which will be described later, is screwed into the screw hole 15. The core pin 1 has an outer diameter that is approximately equal to the outer diameter of the coated optical fiber C, and its tip is tapered into a conical shape. A screw 11+A is cut on the outer periphery of the rear end to be screwed into the screw hole 13 of the upper die 10B. Further, the upper mold 10B is provided with an injection hole 15 at its upper end for injecting plastic.

The procedure for manufacturing a ferrule using such a mold 10 will be described below.

First, one end of a glass pipe with a predetermined length, the inner diameter of which is approximately equal to the bare optical fiber F, is inserted into the holding hole 12A of the lower mold 10A and temporarily fixed, and then the upper mold 10B is overturned and the lower mold 10A and the upper mold 10B are assembled. l) Secured in one body with bolts not shown. After that, turn the core pin 1, which is screwed onto the upper mold 10B, in the downward direction and hold the upper end of the glass pipe with the tip, and insert the glass pipe and the core bottle into the mold cavity 11.
A, arrange in a straight line within 11B. In this state, inject plastic into the injection hole 15 to mold the ferrule body, pull out the core pin 1, and cut the tip of the glass pipe at the tip of the ferrule body flush with the end surface of the ferrule body. A ferrule body 1 as shown in Figures (A) and (B) is manufactured.

(Effects of the Invention) As explained above, in the optical connector ferrule of the present invention, the fiber insertion hole into which the bare optical fiber is inserted is made of a glass pipe, and the length of the insertion hole is determined by molding the core pin. Since it is manufactured without restrictions, it is possible to freely obtain a sufficient length necessary for fixing the bare optical fiber and the ferrule, and a sufficient length necessary for polishing the ferrule tip smoothly. Furthermore, since the inner circumferential side of the ferrule tip is made of glass, the thermal expansion coefficients of the inner circumferential side and the bare optical fiber can be made equal, making it possible to use a ferrule with a bare optical fiber fixed to it for a long period of time. However, bare optical fiber often protrudes from the tip of the ferrule.

[Brief explanation of the drawing]

FIGS. 1A and 1B are longitudinal cross-sectional views and side views of a ferrule for optical connectors of the present invention, and FIG. 2 is a cross-sectional view of a mold used in manufacturing the ferrule of the same embodiment. FIG. 3 is a front view showing the terminal portion of the optical fiber. 1...Ferrule body, 2...Bare optical fiber insertion hole, E...Metal pipe, 10...
...Mold mold, 10A...Lower mold, 10
B... Upper type, 11 people 111B... Type <
11I...core pin, 15...resin injection hole. Figure 1 (a) Figure 1 (b) Figure 3

Claims (1)

[Claims] In a ferrule having a bare optical fiber insertion hole and a coated optical fiber insertion hole communicating with the insertion hole, the bare optical fiber insertion hole is made of a glass body having an inner hole of the same size as the bare optical fiber at least on the inner peripheral side thereof. A ferrule for an optical connector characterized by the following structure: