GB1558914A - Fibre optic connectors - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO FIBRE OPTIC CONNECTORS (71) We STANDARD TELEPHONES AND CABLES LIMITED, a British Company of 190 Strand, London, W.C.2. England do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The problem of accurate end-on alignment is of great significance in a connector for fibre-optic cable, since if there is any mis-alignment the loss of light could easily reach serious proportions.

According to the invention there is provided a connecting arrangement for optical fibres, in which each of a pair of optical fibres to be connected is terminated in a right cylindrical ferrule whose end face is flat with the fibre ends each centrally located in its said ferrule, in which the two ferrules abut within a sleeve-like enclosure, in which within the enclosure there is provided a generally cylindrical or tubular spring arrangement which is of smaller diameter between its ends than at its ends, and in which the smaller diameter portion of the spring arrangement grips the abutting ends of the ferrules to maintain them in accurately-aligned end-on relation.

Embodiments of the invention will now be described with reference to the accompanying drawing, in which Figure 1 is a sectioned view of a connector for optical fibres embodying the present invention, while Figure 2 is a preferred version of the spring used in Figure 1. However, our invention is not limited to its fibre optics appliction.

Each of the optical fibres is a clad and coated fibre 1, 2, terminated by a small metallic ferrule 3, 4. Each of the ferrules is a right cylinder, and its fibre is received in it with the fibre bared and centrally located in one end of the ferrule. Thus when the two ferrules abut in accurate alignment the two fibre ends are accurately aligned with each other so that light transfer occurs with very little loss of light. Each of these ferrules has its non-abutting end enlarged, rather resembling the head of a nail.

The left hand ferrule 3 extends through the end of a sleeve-like enclosure 5 and is held in place therein by a screwed-on tubular member 6. The other ferrule and the coated fibre 2 are received in another tubular member 7 with a screwed-in enclosure member 8. Within the member 7 there is a coil spring 9 which urges the ferrule 4 leftwards to provide the equivalent of contact pressure. This member 7 screws into the end of the sleeve 5, and its inner extension portion 10 acts on a bung 11 which embraces the ferrule 4.

Within the sleeve 5 there are three flat bowed springs 12, 13 whose bowed regions bear on the inner ends of the two ferrules to assist in the accurate location of the ferrules one with respect to the other, and to clamp the ferrules together. These springs are uniformly distributed about the axis of the ferrules, and there may in some cases be more than three of them. If desired the springs can be fastened to rings at one or both ends so as to provide a single unitary piece part.

The member 7 is shown as screwed into the end of the sleeve 5. being located therein by the shoulder 14-.- however a simple plug in connection may in some cases be usable. This latter would especially apply where the arrangements shown are within a two-part connector assembly held together by an external screw-coupling. Such an arrangement would be especially suitable in the case of multi-way connectors.

Figure 2 shows an alternative form of spring arrangement for use within the sleeve 5. This spring is a single tubular member, slotted lengthwise as at 20, and bowed inwards as at 21 between its ends so that the gripping action effected on the two ferrules is substantially continuous. Note also that this spring arrangement has substantially right cylindrical end portions 22 and 23 to provide location within the sleeve 5. When the spring means is inserted into the sleeve 5 it is squeezed slightly, so that it exerts same pressure on the ferrules when the latter abut.

WHAT WE CLAIM IS: 1. A connecting arrangement for optical fibres, in which each of a pair of optical fibres to be connected-is terminated in a right cylindrical ferrule whose end face is flat with the fibre ends each centrally located in its said ferrule, in which the two ferrules abut within a sleevelike enclosure, in which within the enclosure there is provided a generally cylindrical or tubular spring arrangement which is of smaller diameter between its ends that at its ends.

and in which the smaller diameter portion of the spring arrangement grips the abutting ends of the ferrules to maintain them in accurately-aligned end-on relation.

2. An arrangement as claimed in claim 1, and in which the spring arrangement consists of at least three spring strips each of which is bowed inwards between its ends, the bowed-inwards portions providing the spring arrangements smaller diameter portion.

3. An arrangement as claimed in claim 2, and in which the spring strips are interconnected by a ring-shaped portion at at least one end of each spring strip.

4. An arrangement as claimed in claim 1, and in which the spring arrangement is a one-piece member of generally cylindrical form but with a longitudinally extending slot between its ends, and with a waisted portion between its ends to provide the smaller diameter portion.

5. A connecting arrangement for optical fibres, substantially as described with reference to Figure 1 or Figures 1 and 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. gripping action effected on the two ferrules is substantially continuous. Note also that this spring arrangement has substantially right cylindrical end portions 22 and 23 to provide location within the sleeve 5. When the spring means is inserted into the sleeve 5 it is squeezed slightly, so that it exerts same pressure on the ferrules when the latter abut. WHAT WE CLAIM IS:

1. A connecting arrangement for optical fibres, in which each of a pair of optical fibres to be connected-is terminated in a right cylindrical ferrule whose end face is flat with the fibre ends each centrally located in its said ferrule, in which the two ferrules abut within a sleevelike enclosure, in which within the enclosure there is provided a generally cylindrical or tubular spring arrangement which is of smaller diameter between its ends that at its ends.

and in which the smaller diameter portion of the spring arrangement grips the abutting ends of the ferrules to maintain them in accurately-aligned end-on relation.

2. An arrangement as claimed in claim 1, and in which the spring arrangement consists of at least three spring strips each of which is bowed inwards between its ends, the bowed-inwards portions providing the spring arrangements smaller diameter portion.

3. An arrangement as claimed in claim 2, and in which the spring strips are interconnected by a ring-shaped portion at at least one end of each spring strip.

4. An arrangement as claimed in claim 1, and in which the spring arrangement is a one-piece member of generally cylindrical form but with a longitudinally extending slot between its ends, and with a waisted portion between its ends to provide the smaller diameter portion.

5. A connecting arrangement for optical fibres, substantially as described with reference to Figure 1 or Figures 1 and 2 of the accompanying drawings.