Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1998-12-17
2001-05-29
Kim, Robert H. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S086000
Reexamination Certificate
active
06238103
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to optical fiber connector assemblies for connecting optical fiber cables and, particularly, to an optical fiber connector assembly to which an optical fiber cable is fixed later to complete an optical fiber connector assembly.
2. Description of the Related Art
Most of the conventional optical fiber connector assemblies require a bonding agent to assemble them in the field and have disadvantages in terms of environment and the number of manufacturing steps. The assemblers demand simpler and fewer manufacturing steps. There are some optical fiber connectors preassembled by optical fiber connector manufactures.
For example, Japanese patent application Kokai No. 7-248433 discloses a push-pull or SC type optical fiber connector. Two such connectors are connected through an adaptor type connector. It is easy to fix an optical fiber to the connector to complete the assembly without any bonding agent.
In the above connector, an optical fiber is fixed at two points by an elastic insert and a collapsible plunger. The elastic insert consists of three elastic balls of the substantially same diameter and placed behind the ferrule. The elastic balls are fitted into a narrow space to fix the fiber element. The collapsible plunger is made as an elongated cylinder and placed behind the elastic insert. The collapsible plunger is then fitted into a narrow cylindrical space so that projections of the collapsible plunger collapse to fix the optical cable.
In the above connector, however, the elastic insert for fixing the fiber element is prone to thermal deformation so that the optical cable is moved in the axial direction. That is, when the ambient temperature changes, the gripping power over the optical cable is lowered because of a difference in thermal expansion between the elastic insert and the optical cable so that the optical cable tends to move in the axial direction. Consequently, the position of the optical cable at the front end of the ferrule is shifted, resulting in the poor optical connection characteristics. (This is called “insertion loss change.”) This insertion loss change is a factor to cause a connection loss of the optical cable. In the above example, the optical cable is fixed at points so that the fixation is unstable. That is, the elastic insert is spherical so that when it is shrunk, the fiber element contacts the balls at small areas. In addition, the projections behind the collapsible plunger occupy only a mere portion so that when the projections are collapsed, the areas that the optical cable abuts on the collapsed projections are small. Consequently, the fixing strength of the optical cable is low. Moreover, there is a large distance between the elastic insert and the collapsible plunger so that the thermal change of the jacket for the optical cable between them is very high, resulting in the weak optical cable and reducing the usable temperature range.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an optical connector assembly with a support member having a low thermal expansion coefficient.
It is another object of the invention to provide an optical connector assembly with a large area to stabilize the fixation of an optical cable.
It is still another object of the invention to provide an optical connector assembly with the fixing areas so close to each other that the thermal contraction or expansion of the optical cable is small.
It is yet another object of the invention to provide an optical connector assembly to which an optical cable is fixed from the side opposite to the ferrule.
According to one aspect of the invention there is provided an optical fiber connector assembly which comprises a ferrule for supporting an optical fiber element of an optical fiber cable; a ferrule holder having an insertion section aligned with the ferrule; a fiber crimper fitted into the insertion section to fix the optical fiber element at a first predetermined area; and a cable holder fitted into the insertion section to fix the optical fiber cable at a second predetermined area.
It is preferred that the first and second predetermined areas are provided in proximity.
According to another aspect of the invention there is provided an optical fiber connector assembly which comprises a ferrule for supporting a front portion of an optical fiber element; a ferrule holder integral with the ferrule and having a first insertion section aligned with the ferrule and a second insertion section having an inside diameter smaller than the first insertion section; a fiber crimper temporarily assembled in the first insertion section and then fitted into the second insertion section to reduce an inside diameter of the fiber crimper for fixing the optical fiber element in a first predetermined area; a cable holder with a front portion temporarily assembled in the first insertion section and then further fitted into the first insertion section to reduce an inside diameter of the cable holder for fixing the optical fiber cable in a second predetermined area, wherein the fiber element is inserted into the cable holder, the fiber crimper, and the ferrule, the fiber crimper is further inserted into the first insertion section while the fiber crimper is inserted into the second insertion section so that the fiber element and the fiber cable are fixed by the fiber crimper and the cable holder, respectively, at areas which are close to each other and have predetermined lengths.
It is preferred that the ferrule and the fiber crimper is formed from a material having a low thermal expansion coefficient. Preferably, the ferrule is made from a resin. Preferably, the ferrule and the ferrule holder are made as a unit. Preferably, the fiber crimper and the cable holder are made as a unit.
It is preferred that the optical fiber connector assembly further comprises a plug frame with a passage opening for supporting the ferrule or the ferrule holder; a spring member for forwardly urging the ferrule; and a device for supporting the spring member.
REFERENCES:
patent: 5381500 (1995-01-01), Edwards et al.
patent: 5668904 (1997-09-01), Sutherland et al.
patent: 5943460 (1999-08-01), Mead et al.
Hirose Electric Co. Ltd.
Kanesaka & Takeuchi
Kim Robert H.
Stafira Michael P.
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