Optical waveguides – Accessories – Attenuator
Reexamination Certificate
1999-04-14
2002-01-22
Rosenberger, Richard A. (Department: 2877)
Optical waveguides
Accessories
Attenuator
C385S023000, C385S053000, C385S056000, C385S060000
Reexamination Certificate
active
06341191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a variable attenuation type optical power attenuator used for an optical fiber communications system. More particularly, the invention relates to an optical power attenuator of a new variable attenuation type in which a pair of ferrules having optical fibers with end surfaces thereof formed to be inclined against a plane perpendicular to the optical axis are oppositely aligned coaxially in the hole of an alignment sleeve. One of the paired ferrules is rotated to change the distance between the optical fiber end surfaces so as to permit continuous change of optical power attenuation and to automatically fix and maintain any desired optical power attenuation position.
2. Description of the Related Art
Referring to FIG.
4
A and
FIG. 4B
, the principle of variable optical power attenuation will be described. The inventor has already proposed an optical power attenuator of the variable attenuation type, which employs the principle, under U.S. Pat. No. 5,136,681.
FIG. 4A
is a sectional view illustrating a setting for a minimum optical power attenuation, while
FIG. 4B
is a sectional view illustrating a setting for a maximum optical power attenuation. A pair of ferrules
8
and
9
with optical fibers, the end surfaces of which are formed to be inclined at an angle &thgr; with respect to a surface perpendicular to the optical axis thereof, are oppositely aligned coaxially in the hole of an alignment sleeve
17
. One of the ferrules, for example, the ferrule
9
, is rotated to change a distance S between the end surfaces of the optical fibers so as to continuously vary the optical power attenuation.
There has been a strong demand for actually using the variable attenuation type optical power attenuator, which has been disclosed under U.S. Pat. No. 5,136,681, for an optical fiber communications circuit or the like of a CATV, etc. Putting this variable attenuation type optical power attenuator to practical use has been facing the following main technological task to be achieved. The variable attenuation type optical power attenuator has to permit easy adjustment or setting to a desired optical power attenuation value, and once the optical power attenuation value has been adjusted or set, this value must not be disturbed by an external force such as mechanical vibration or impact.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a variable attenuation type optical power attenuator that has successfully achieved the task in the conventional variable attenuation type optical power attenuator with the rotating ferrule as set forth above.
It is a further specific object of the invention to provide a new variable attenuation type of optical power attenuator that allows the amount of optical power attenuation to be continuously changed and also enables a set optical power attenuation point to be automatically fixed and maintained. In this new variable attenuation type of variable optical power attenuator, a face ratchet of a ratchet ring installed on a fixed ferrule housing such that it may linearly move in the axial direction is automatically engaged with or disengaged from a face ratchet of a ratchet ring provided in association with a rotating ferrule housing by rotating the rotating housing.
It is another object of the invention to provide a variable attenuation type optical power attenuator with a latching ratchet that can be used as an FC type variable attenuation type optical power attenuator.
To these ends, according to one aspect of the invention, there is provided a variable attenuation optical power attenuator with a latching ratchet, including: a fixed ferrule and a rotating ferrule having the end surfaces thereof polished, together with central optical fibers thereof, to be formed into inclined surfaces; an alignment sleeve which receives the fixed and rotating ferrules with optical fibers in such a manner that the distal ends thereof are opposed to each other and the ferrules may be relatively rotated; a fixed housing which restricts the rotation of the fixed ferrule and which receives the alignment sleeve and the rotating ferrule; a rotating housing which has a face ratchet facing the fixed housing and which is joined by a threaded portioned portion such that it may rotationally move forward or backward in relation to the fixed housing while it is coupled to the fixed ferrule to restrict the rotation of the fixed ferrule; a ratchet ring which has its rotation restricted by the fixed housing, which is joined such that it may move forward or backward while being urged by a first spring toward the rotating housing, and which has a face ratchet engaging a face ratchet of the rotating housing; and a second spring provided between the rotating ferrule with the optical fiber and the rotating housing; wherein the rotating housing is rotated to change the relative rotational angle with respect to the fixed housing so as to adjust the distance between the optical fiber end surface of the fixed ferrule and that of the rotating ferrule.
According to another aspect of the invention, there is provided a variable attenuation type optical power attenuator with a latching ratchet, including: a pair of ferrules with optical fibers having the end surfaces thereof polished, together with the central optical fibers thereof, to be formed into inclined surfaces and which are respectively provided with flanges having engaging portions on the outer peripheries thereof; an alignment sleeve which receives the fixed and rotating ferrules with optical fibers in such a manner that the ends thereof are opposed to each other and the ferrules may be relatively rotated; a fixed housing which has an engaging portion which engages the flange of the fixed ferrule to restrict the rotation, a portion for receiving the alignment sleeve, a coupling threaded portion, and a rectilinear joining portion; a rotating housing which has a face ratchet having many (n) teeth, a threaded portion engaging the coupling threaded portion of the fixed housing, and an engaging portion which engages the engaging portion of the flange of the rotating ferrule with the optical fiber; a ratchet ring equipped with a face ratchet which engages the face ratchet of the rotating housing and a rectilinear joining portion which engages the rectilinear joining portion of the fixed housing; and first and second coil springs; wherein the fixed and rotating ferrules, which have been coupled by the alignment sleeve, are inserted in the fixed housing by joining the flange of the fixed ferrule to the rectilinear joining portion; the rotating housing is joined by a threaded portion to the fixed housing with the second coil spring inserted between the flange of the rotating ferrule with the optical fiber and the rotating housing; and the ratchet ring is engaged with the rectilinear joining portion of the fixed housing with the first coil spring inserted between the rotating housing and the ratchet ring, and the face ratchet is opposed to the face ratchet of the rotating housing.
In a preferred form of the variable attenuation optical power attenuator with the latching ratchet; each time the rotating housing is turned by 2&pgr;/2n, the ratchet ring automatically moves linearly in the axial direction along the surface of the face ratchet to disengage the face ratchets; and when the ratchet ring is brought back to a home position thereof by the coil spring to re-engage the face ratchets, the rotational angle of the rotating housing is shifted to adjust the optical power attenuation value on at a pitch of 1/N (N =Number of the teeth of each of the face ratchets), and the adjusted rotational angle can be fixed and maintained.
In another preferred form, the outer end surfaces of the fixed housing and the rotating housing are respectively provided with engaging portions such as threaded portions that engage optical connector plugs or optical connector adapters to constitute an FC variable attenuation type optical power attenuator with a lat
Frank Robert J.
Kelemen Gabor J.
Nguyen Sang H.
Rosenberger Richard A.
Seikoh Giken Co. Ltd.
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