A Kind of Tunable ST Connector and Tuning Process
Field of the Invention
The present invention relates to a connector for use in optical fiber communication, particularly a tunable ST connector, as well as a tuning process by means of the same.
Background of the Invention
In all prior art ST connectors having a zirconia ferrule, after assembly, the position of a ferrule with respect to a locating key is fixed and not adjustable. Concentricity error, if any, will therefore lead to a high insertion loss, and nothing could be done to improve it. Inasmuch, the common deficiencies of the prior art products lie in a high insertion loss, an unstable product quality, and a high reject rate of products. As is common knowledge, when two connectors are butted, the concentricity of optical fiber at both ends is what counts first, as may cause an insertion loss. Therefore, there is a very high requirement as respects the concentricity of ferrules, which increases the difficulty, as well as the cost, of production.
The object of the present invention is to provide a new and original tunable ST connector, to overcome all the above-said prior art shortcomings, and to lower the insertion loss when ferrules are butted; so that a very satisfactory butting effect can be obtained under only ordinary machining accuracy. Another object of the present invention is to provide a tuning process, to ensure the assembling quality of optical fiber communication lines during butting of connectors.
Summary of the Invention
The tunable ST connector according to the present invention comprises a plastic boot, a crimp ring, a coupling nut, and a dust cap, wherein, instead of a commonly used ferrule in the prior art, there are provided a metal backbone which can revolve round its centre line and a tunable ring, said backbone having at one end an internal round hole into which a ferrule may be inserted, and a flange formed at the same end; while at the other end, there is provided a second internal round hole for optical fibre to go through. The said tunable ring is just fit to be slipped over one end of the said backbone to be held on the said flange. Said flange and said tunable ring are further provided with mutually engaging structural means so that, with the help of an elastic means, the two are constantly engaged. If a special tuning adjustment tool is used to
push and rotate the said tunable ring, depending on adjustment of the relative location between the said backbone and the said tunable ring and by means of related instruments, it is possible to find an optimal location, where two butting connectors reach an optimal concentricity and best transmission of optical signals is ensured.
In one embodiment of the present invention, the said flange comprises several notches, and the said tunable ring is provided on its internal side with a stepped edge just for the said flange to rest on; at the end of the tunable ring facing the flange, there are formed inwardly extending lugs just to engage with the said notches formed in the said flange. Moreover, the tunable ring is further provided with slots in its outer surface, so as to match corresponding hogs formed in one end of a tuning adjustment tool, to realize adjustment. The number of the said notches in the flange of the backbone can be between 2 and 24, so as to optimize concentricity adjusting results (Figure 4 shows six notches, just as an example). The elastic means to help engage the said backbone flange and the said tunable ring can be a spring, which is seated upon a C-ring fitted into a slot in the said backbone, while its other end just rests upon the base end of the said tunable ring. In this way, it makes possible to tune the said ring into several positions, ranging from 2 to 24, to find the optimal concentricity adjustment.
The tunable ST connector according to the present invention further comprises a special tuning adjustment tool, knurled at one end on the circumference and having at the other end hogs just to match with the said slots formed in the outer surface of the said tunable ring, so as to facilitate adjustment. The number of the said hogs depends on need.
The present invention further relates to a taring process used when two optical fibre connectors are butted; said process comprising: To find by means of instruments an optimal concentricity; to insert the tuning adjustment tool, so that the hogs at its one end engage into the corresponding slots provided in the said tunable ring; then push and rotate the said tool, to first disengage the said tunable ring from the said backbone, try all subsequent adjustment points until an optimal point is reached, then engage them.
The tunable ST connector according to the present invention has the following advantages in comparison with prior art products: Tuning steps can be 2 to 24, each step corresponding to a rotation by 180° to 15°; therefore an optimal concentricity in butting ferrules can be reached; hence, quality acceptance ratio of the ST connector production is also much raised; requirement as to concentricity accuracy of ferrules is thus lowered. Experiments show that the UPC end insertion loss of the tunable ST connector according to the present invention is =≤0.15 dB.
Brief Description of the Drawings
The above and other objects of the present invention, as well as its various advantages, will be clearly seen in the following description in connection with the accompanying drawings, in which:
Figure 1 is an exploded assembly illustration of the tunable ST connector according to the present invention;
Figure 2 is an illustration of a tunable ring in the tunable ST connector according to the present invention;
Figure 3 is the above-mentioned tunable ring as viewed from another angle;
Figure 4 is an illustration of a metal backbone of the tunable ST connector according to the present invention;
Figures 5 and 6 show each an illustration of assembly of the said tunable ring and the said metal backbone of the tunable ST connector according to the present invention; and
Figure 7 is an illustration showing a tuning adjustment tool used for the tunable ST connector according to the present invention.
Detailed Description of an Embodiment
With reference to Figs. 1, 2, 3, 4, 5, the tunable ST connector according to the present invention comprises a plastic boot 9, a crimp ring 8, a coupling nut 2, and a dust cap 1, wherein instead of a prior art ferrule, there are provided a metal backbone 5 which can revolve round its center line and a tunable ring 4. Said backbone 5 has at its one end an internal round hole 51 for a ferrule 3 to insert and a flange 54 formed at the same end; at its other end, there is formed a second internal round hole 52 for optical fibre to go through. The said tunable ring 4 can be slipped over one end of the said backbone 5, just to rest on the said flange 54. The said flange 54 and the said tunable ring 4 are further provided with structural means for mutual engagement, so that the two are constantly engaged with the help of an elastic means.
Said backbone 5 is provided in its outer surface with an annular slot 53, for a C- ring 7 to fit in (see Figure 1); and as the said elastic means mentioned at the end of the foregoing paragraph, a spring 6 is used, which is slipped over the backbone 5, with its one end resting on the said C-ring 7 and the other end seated on the base end 44 of the said tunable ring 4 fitted over one end of the backbone 5.
Further, the said flange 54 comprises several notches 541, and the tunable ring 4 is provided on its internal side with a stepped edge 42; when the said tunable ring 4 is slipped over the said backbone 5, the said stepped edge 42 is just for the said flange
54 to rest on. At the end of the tunable ring 4 opposite to its base 44, there are formed inwardly extending lugs 41, to engage with the said notches 541 formed in the said flange 54. In addition, in the outer surface of the said tunable ring 4, there are formed slots 43, to match the corresponding hogs 101 formed at one end of a tuning adjustment tool 10, so as to facilitate adjustment.
In one embodiment according to the present invention, the said flange 54 possesses 6 notches 541, so that by means of the said special tuning adjustment tool 10, six different adjustment points can be tried to ensure optimal concentricity adjustment during butting of connectors.
The present invention also comprises a special tuning adjustment tool 10, which is provided with a knurled surface 102 at one end, while at the other end, there are formed hogs 101 matching the said slots 43 formed in the outer surface of the said tunable ring 4, so as to engage with the tunable ring for adjustment.
The present invention further comprises a process for concentricity adjustment during butting of optical fibre connectors, said process comprising: To find by means of instruments an optimal concentricity; to insert the tuning adjustment tool 10 so that the said hogs 101 fit into the said slots 43 in the said tunable ring 4; then push the said tool 10, so that the said tunable ring 4 and backbone 5 are disengaged; to turn the said tunable ring 4, trying all subsequent adjustment points, and finally to engage the tunable ring 4 and the backbone 5 again when an optimal concentricity is reached.