Optical waveguides – With disengagable mechanical connector – Optical fiber/optical fiber cable termination structure
Reexamination Certificate
1999-11-15
2001-01-30
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber/optical fiber cable termination structure
C385S060000, C385S072000
Reexamination Certificate
active
06179481
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to connectors for optic fibre cables.
2. Acknowledgement of Prior Art
Optic fibre cable is becoming more and more important in the transmission of data over distance but optic fibre cables present special problems in connecting one cable to another or to an appliance for receiving or transmitting light. Particular problems that arise are the proper alignment of the fibres and the attainment of a tight fit in the connection. When any plug is connected into a socket it is rarely a completely tight fit at its leading face with the adjacent surface of the socket. For most plugs this is not important since connection is through the circumference of the respective plug and socket. For fibre optic cables however, connection is through the flush faces of the optic fibres. If one face does not make perfect connection with the adjacent face of a complementary member light is lost and quality of transmission is affected. It is therefore extremely important that, for fibre optic cables an optimized tight fit of the face at the end of the cable is desirable. Various attempts have been made to provide such an optimized fit and some of these are set out in:
U.S. Pat. No. 5,717,802
Briggs et al.
Feb. 10, 1998
U.S. Pat. No. 5,444,806
deMarchi et al.
Aug. 22, 1995
U.S. Pat. No. 5,097,525
Garcia et al.
Mar. 22, 1992
U.S. Pat. No. 4,834,487
Abendschein et al.
May 30, 1989
U.S. Pat. No. 4,793,683
Cannon, Jr. et al.
Dec. 27, 1988
U.S. Pat. No. 4,193,663
Timmermann
Mar. 18, 1980
U.S. Pat. No. 5,414,790
Lee et al.
May 9, 1995
U.S. Pat. No. 5,594,825
Kawasaki et al.
Jan. 14, 1997
U.S. Pat. No. 5,542,015
Hultermans
July 30, 1996
U.S. Pat. No. 5,230,032
Muzslay
July 20, 1993
U.S. Pat. No. 5,212,752
Stephenson et al.
May 18, 1993
U.S. Pat. No. 5,170,452
Ott
Dec. 8, 1992
U.S. Pat. No. 4,798,431
Clark et al.
Jan. 17, 1989
U.S. Pat. No. 4,812,007
Lukas
Mar. 14, 1989
These patents are exemplary of the large number of fibre optic cable connectors which have been provided. Of these patents some of them, for example U.S. Pat. No. 4,834,487, show optic fibre cable plugs in which the plug itself is pressed forwardly by a spring so that the plug is biased into the socket. This is not a wholly satisfactory solution to the problem since the end of the fibre optic cable itself may become worn or may not project far enough from the plug to make a perfect fit with its mating member. It would be preferable to bias the fibre optic cable itself within the plug so that when the plug is seated firmly in the socket the fibre optic cable is biased to project from it towards its mating member. Such a situation is described in U.S. Pat. No. 5,717,802 to Briggs et al. U.S. Pat. No. 5,717,802 shows a spring biased fibre optic cable projecting from a plug body. A bearing for the spring is provided by shoulders of cantilevered members of the plug body. The cantilevered members, are snapped into position and are held in that position by means of a shoulder formed in the casing of the optic fibre cable.
SUMMARY OF THE INVENTION
It would clearly be desirable to provide a connector which is inexpensive, not unduly subject to wear and stress, and easily connectible to an end of an optic fibre and its casing without the need for the provision of machining at a precise distance from the end of each cable.
Thus according to the invention there is provided a fibre optic plug connector comprising an optic fibre cable having a flexible protective casing along its length and a rigid jacket about the circumference of an end portion, an unobstructed end face of the fibre being for connection to a complementary member; a collar about the fibre optic cable at a transition between said protective casing and said rigid jacket, the rigid jacket projecting forwardly out of the collar; a plug sleeve to receive the collar therein having an axial passage therethrough and having forward and rearward sections, the forward section being formed as a plug to fit a complementary socket of the complementary member, the sleeve having an internal shoulder shaped to engage a forward end of the collar in non-rotational relationship such that said rigid jacket projects forwardly from the plug sleeve; a helical spring freely about said protective casing rearwardly of the collar and axially aligned within said rearward section of the plug sleeve; a support sleeve about said protective casing rearwardly of said spring, said support sleeve having a radially outwardly projecting shoulder about a forward end portion thereof; and a housing sleeve having a forward open end portion, the housing sleeve covering the rearward section of the plug sleeve and the forward end portion of the support sleeve, snap fastening means being provided between the housing sleeve and the plug sleeve to fasten them together such that the spring is compressed between the collar and the support sleeve to bias the optic fibre forwardly.
Conveniently, the plug sleeve may be formed of plastic material having some resilience and may have an elongate portion of its rearward section cut away for visibility in original assembly of the connector, i.e. it may comprise only a section of cylindrical sleeve. Some material costs may be saved by such cut-away portion and the cut away may provide additional resilience.
The snap fastening means between the housing sleeve and the plug sleeve may conveniently comprise a lug on one of the members to cooperate with a slot or aperture in the other of the members to hold them firmly together with the spring in compression. Conveniently the lug may project from the rear section of the plug sleeve into a complementary aperture on the sleeve housing. The rear section of the plug sleeve may have sufficient resilience so that, in assembly, the housing sleeve may be telescoped forwardly over the rear section of the plug sleeve until the lug of the aperture match and the lug is biased by the resilience of the rear section of the plug sleeve into the aperture.
Conveniently, a resilient ornamental cover sleeve may be elastically fitted over the housing sleeve in the region of the snap fastening to cover it both for ornamental purposes and to guard against accidental disconnection.
It is of considerable importance that the leading face of the optic fibre be clean and polished for optimum transmission of light. Therefore, for transport purposes it is normal to provide a cover cap over the rigid jacket and the free unobstructed end face of the fibre. There have been known instances of people attempting to connect the fibre optic connectors without removing such end caps. Therefore, conveniently, an end cap is provided with an enlarged head portion to bring attention to its presence.
The leading end of the rigid jacket may be bevelled to allow for optimal connection between the face of the optic fibre and the member to which it is to be connected. For the same purpose, the end of the optic fibre may be slightly enlarged in lens formation to direct light optimally. Preferably the enlarged end of the optic fibre is formed integrally by molding of the heated optic fibre. The resulting head may be polished. Suitably the enlarged head is hemispherical.
REFERENCES:
patent: 4193663 (1980-03-01), Timmermann
patent: 4793683 (1988-12-01), Cannon, Jr. et al.
patent: 4798431 (1989-01-01), Clark et al.
patent: 4812007 (1989-03-01), Lukas
patent: 4834487 (1989-05-01), Abendschein et al.
patent: 5097525 (1992-03-01), Garcia et al.
patent: 5170452 (1992-12-01), Ott
patent: 5212752 (1993-05-01), Stephenson et al.
patent: 5230032 (1993-07-01), Muzslay
patent: 5414790 (1995-05-01), Lee et al.
patent: 5444806 (1995-08-01), deMarchi et al.
patent: 5542015 (1996-07-01), Hultermans
patent: 5594825 (1997-01-01), Kawasaki et al.
patent: 5717802 (1998-02-01), Briggs et al.
patent: 6010250 (2000-01-01), Sung
Palmer Phan T. H.
Ridout & Maybee
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