JPS6041528Y2 - Plug for fiber optic connector - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a plug for an optical fiber connector for visually connecting optical fibers in the field of optical fiber communication using optical fibers as a transmission medium.

The development of optical fiber communication systems that use optical fibers as transmission media is progressing, but in order to form such communication systems, the optical fiber connectors that connect optical fibers are required to have low loss and high reliability. It is a very important device.

To date, optical fiber connectors such as the sleeve type, double eccentric tube type, and ■conventional type have been put into practical use.

Of these, the sleeve method and the conventional method attach the optical fibers to the center of the plug by some method, and connect the optical fibers to each other via an adapter (called centering or alignment) or a groove.

The centering method uses a special jig and is performed while viewing a microscope or a television monitor connected to it.

However, in recent years, with the development of machine tools such as micro drills and improvements in recording technology, the coaxiality with the plug outer diameter has been reduced to 2 μm.
It has become possible to drill holes with an accuracy of approximately ±1 μm in diameter of one nozzle.

Plugs that have undergone this kind of processing are called precision nozzle type plugs, and among optical fibers, quartz fibers with excellent core and cladding outer diameter dimensional accuracy, circularity, coaxiality, etc. By using this nozzle-type plug for fibers, MRT fibers, etc., it is no longer necessary to fix the optical fiber to a fine movement table and perform centering for relatively fine adjustment.

A side sectional view of a conventional nozzle-type optical fiber connector plug is shown in FIG. 1, and FIG. 2 is an enlarged view of the internal structure of the plug.

1 and 2, 1 is an optical fiber, 2 is a primary coating of the optical fiber with a necessary plastic such as urethane resin, epoxy resin, silicone resin, etc., 3 is polyamide, polyethylene, fluororesin, etc. Optical fiber secondary coating made of a required plastic such as polycarbonate; 4 is an optical fiber core supplementary angle metal sleeve; 5 is a nozzle-type plug having a nozzle-shaped tube opening A; 6 is a nozzle-shaped tube opening A and primary coating 2.2 Next coating 3, metal sleeve 4
This is a thermosetting adhesive that fills the gap H between the inner peripheral surface of the plug 5 and the outer peripheral surface of the metal sleeve 4.

In this structure, an optical fiber core complementary metal sleeve 4 having the same cross-section A is adhesively fixed to a required plastic such as polyamide, polyethylene, fluororesin, polycarbonate, etc., which is the secondary coating 3 of the optical fiber.

In this plug 5, when the central axis of the nozzle-shaped cylinder mouth A and the central axis of the optical fiber 1 installed in the metal sleeve 4 do not coincide, the optical fiber 1 is fixed by being curved as shown in Fig. 2. be done.

A thermosetting adhesive 6 is applied around the curved optical fiber 1.
However, when the thermosetting adhesive 6 is cured, curing shrinkage of at least 7 to 8% occurs, which acts on the optical fiber 1 as shear stress, reducing the optical fiber's breaking strength. When the above stress is applied, the optical fiber 1 breaks.

Most of the rupture points are at portions 1a or 1b.

In both the la and lb portions, the primary coating 2 has been peeled off, so the strength is about one order of magnitude lower than in the case where the primary coating 2 is peeled off.In addition, since the optical fiber is curved, the thermosetting It is easy to break when subjected to stress due to adhesive curing and shrinkage.

Conventional plugs have the drawbacks mentioned above.

This invention was developed to eliminate the drawbacks of the conventional method, and its feature is that the optical fiber is first coated with a necessary plastic such as urethane resin, which covers the optical fiber that is installed in the plug that has a nozzle-like opening. and an optical fiber secondary coating made of a required plastic such as polyamide, and an optical fiber complementary metal sleeve that covers this secondary coating, so that one end surface of the optical fiber primary coating and secondary coating is aligned with the optical fiber core. A gap formed between the inner circumferential surface of the plug and the outer circumferential surface of the optical fiber reinforcing metal sleeve is inserted into the plug so as to protrude from one end of the complementary metal sleeve toward the mouth of the nozzle. And, by filling a thermosetting adhesive between the nozzle-shaped cylinder mouth and one end surface of the metal sleeve and fixing the metal sleeve, it is possible to almost completely eliminate the breakage that occurs in the conventional method. be.

Examples of this invention will be described in detail below with reference to the drawings.

FIG. 3 is a side sectional view of a nozzle type optical fiber connector plug according to this invention.

In the figure, the - of the primary coating 2 and the secondary coating 3 are peeled off from the same cross-sectional opening, and the ends of the primary coating 2 and the secondary coating 3 are placed on the side of the nozzle-shaped cylinder opening A from the one end surface of the metal sleeve 4. Even if the thermosetting adhesive 6 cures and contracts by protruding and fixing with adhesive, even if shear stress is applied to the optical fiber 1,
The primary coating 2 and the secondary coating 3 slightly protrude from the optical fiber core complementary metal sleeve 4 toward the nozzle-shaped tube mouth A side.
This absorbs the deformation strain, and the shear stress applied to the optical fiber 1 is significantly reduced.

Therefore, breakage of the optical fiber due to curing shrinkage of the thermosetting adhesive can be almost completely eliminated.

[Brief explanation of the drawing]

FIG. 1 is a typical internal structure diagram of a conventional nozzle type optical fiber connector plug, FIG. 2 is an enlarged view of the plug shown in FIG. 1, and FIG. 3 is a diagram showing an embodiment of this invention. In the figure, 1 is an optical fiber, 2 is a primary coating, 3 is a secondary coating, 4 is an optical fiber core complementary metal sleeve, 5 is a precision nozzle-type plug, 6 is a thermosetting adhesive, and A is a nozzle-shaped At the tube mouth, H is the gap. Note that the same or equivalent parts in the figures are indicated by the same reference numerals.

Claims (1)

[Scope of utility model registration request] A primary coating of the optical fiber with a required plastic such as urethane resin to coat the optical fiber installed in a plug having a nozzle-shaped tube opening, a secondary coating of the optical fiber with a required plastic such as polyamide, and covering this secondary coating. The optical fiber reinforcing metal sleeve is attached to the plug so that one end surfaces of the optical fiber primary coating and secondary coating protrude from one end of the optical fiber supplementary angle metal sleeve toward the nozzle-shaped tube mouth side. and a thermosetting adhesive between the gap formed between the inner circumferential surface of the plug and the outer circumferential surface of the metal sleeve for reinforcing the optical fiber core, and between the nozzle-shaped tube mouth and one end of the metal sleeve. A plug for an optical fiber connector characterized by being filled with an adhesive and fixed.