GB2133172A

GB2133172A - Optical cable connector assembly

Info

Publication number: GB2133172A
Application number: GB08300173A
Authority: GB
Inventors: Stephen John Turpin
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1983-01-05
Filing date: 1983-01-05
Publication date: 1984-07-18
Also published as: GB8300173D0; GB2133172B; AU2384384A; AU559035B2

Abstract

A cable connector assembly consisting of a number of single optical fibre cables (17) independently attached to a multiway connector element provides an anchorage for the cables by means of individual cable collars (22) each of which is secured to the strength member of its associated cable and butts against a slotted anchorage plate (23) retained within the connector element shell (10). The connector also comprises a support plate (15) for terminations of the optical fibres of the cables (17). <IMAGE>

Description

SPECIFICATION Optical cable connector assembly This invention relates to a cable connector assembly consisting of a plurality of optical fibre cables terminating in a single connector element adapted for connection to a co-operating multiway optical device which may incorporate an array of photo-detectors, or light sources, or further optical fibres. The invention is particularly concerned with a way of anchoring the individual cables within the connector element in a manner that ensures that when a cable is tensioned the load is transferred to the connector element at an intermediate point within the element so that the optical fibre ahead of this point, as far as the fibre termination, is not loaded by the cable tensioning.

According to the present invention there is provided a cable connector assembly consisting of a plurality of cables, each containing within an outer sheath a single packaged optical fibre surrounded by strands of material forming a strength member, terminated in a single multiway connector element that is common to the cables and is adapted for mating with a co-operating multiway optical device, which element includes a connector shell provided intermediate its ends with an internal slotted cable strength member anchorage plate through whose slots the cables freely pass, and provided at its mating end with a support plate for terminations of the optical fibres of the cables, wherein between two plates each cable is provided with a collar which is firmly attached to the cable strength member strands, is dimensioned so as to be unable to pass through the slots of the anchorage plate and is located on the cable in a position such that, when the cable is tensioned, the load is carried by the anchorage plate instead of being transmitted further up the cable to the support plate via the fibre termination.

A feature is that should any of the cables prove unsatisfactory, or for some other reason need replacing, this can be done without disturbing the means by which the other cables are anchored to the connector element.

There follows a description of a cable connector assembly embodying the present invention in a preferred form. The description refers to the accompanying drawings in which: Figure 1 depicts a longitudinal section of the connector element of the assembly, Figures 2, 3 and 4 depict transverse sections on the lines A-A, B-B and C-C of Figure 1 respectively, and Figure 5 depicts on a larger scale, a longitudinal section of one of the cable retention collars of the assembly.

The connector shell 10 of a connector element has three inwardly directed flanges 11, 12 and 13.

Flange 11 at the forward end of the connector element supports a slotted disc 14 which cooperates with an apertured plate 1 5 in retaining a set of optical fibre terminations 1 6. These may be jewelled ferrule terminations of the type described in our earlier patent specification No. 1 480445 or expanded beam terminations. In this particular case the connector element is designed for 12 single fibre cables 1 7 and the ferrules 1 6 are arranged in two rows and two columns intersecting at right angles as is shown in Figure 2.

The slots in the disc 14 allow the individual ferrules to be removed from the disc for replacement without having to detach the ferrule from its cable. Each ferrule is provided with an integral collar 1 8 which is large enough to be unable to go through the slots 19 (Figure 2) in the disc 14. A key 20 prevents the disc 14 from rotating. The disc and plate are held in position against the flange 11 by means of a screwthreaded retaining ring 21.

Surrounding the forward end of the connector shell 10 is a captive nut 1 Oa by which the connector element is secured in mating relationship with a co-operating multiway optical device (not shown).

Each cable 1 7 has a collar 22 to which the cable strength member is firmly attached. These collars abut the forward facing surface of a slotted anchorage plate 23, which in turn is held against the forward facing surface of flange 12 of the connector shell 10 by a screw-threaded retaining ring 24. The slots 25 (Figure 3) in the anchorage plate are dimensioned to accept the cables. Four of the slots are deep enough to accept two cables each, while the other four slots each accept one cable. One of the deeper slots also fits over a key 26 to stop the anchorage plate from rotating.

To the rear of the anchorage plate the twelve cables pass through a sealing gland formed by an elastomeric cylindrical plug 27 with twelve equispaced longitudinal holes each large enough to accept the individual cables. The forward end of the plug rests against a ring 29 which in turn rests against the flange 1 3 of the connector shell 10, and the plug is axially compressed by screwing in a gland compression nut 30 thereby causing the holes to collapse on to the cables and form a seal.

When the plug 27 is not in the shell, and is not axially compressed, it may be resilient enough for any one of its holes to be expanded sufficiently to permit a collar 22 on a cable 1 7 to be passed through it provided that the collars are not so very much larger in diameter than their cables. This means that it is possible to remove one of the cables from the plug and replace it with another without removing the collar from either cable.

Alternatively each hole may communicate with the outer curved surface of the plug by means of a radiaily extending slit 28 (Figure 4), enabling a cable to be slotted into its hole in the plug.

The construction of an anchorage collar 22, and the manner by which it is attached to the strength member of its cable, is depicted in greater detail in Figure 5. Each optical fibre cable 1 7 has a glass optical fibre 32 (typically made of silica) packaged in one or more layers 33 of plastics material to protect its surface. Surrounding the plastics packaging 33 are strands 34 of high modulus plastics material, such as the aramid polymer sold under the trade mark KEVLAR, to form the cable strength member, and the whole is encased in a plastics sheath 35. The anchorage collar 22 is composed of two parts comprising a central annular slug 36 and a surrounding thimble 37. The slug is fitted over the cable sleeving, and then the sleeving is stripped back as far as the forward end of the slug to expose the underlying strands strength member strands 34. These are splayed out around the forward end and taken straight back down the sides of the slug. Then the thimble is fitted over the exposed plastics packaging 33.

The skirt of the thimble is just large enough to pass over the strength member strands covered outer surface of the slug and is secured in pcsition by crimping to the slug.

Claims

1. A cable connector assembly consisting of a plurality of cables, each containing within an outer sheath a single packaged optical fibre surrounded by strands of material forming a strength member, terminated in a single multiway connector element that is common to the cables and is adapted for mating with a co-operating multiway optical device, which element includes a connector shell provided intermediate its ends with an internal slotted cable strength member anchorage plate through whose slots the cables freely pass, and provided at its mating end with a support plate for terminations of the optical fibres of the cables, wherein between two plates each cable is provided with a collar which is firmly attached to the cable strength member strands, is dimensioned so as to be unable to pass through the slots of the anchorage plate and is located on the cable in a position such that, when the cable is tensioned, the load is carried by the anchorage plate instead of being transmitted further up the cable to the support plate via the fibre termination.

2. An assembly as claimed in claim 1 , wherein each collar consists of a slug and thimble, the slug having an axial hole through which the cable passes with its strength member strands splayed out around one end and folded back along the outer surface of the slug to be held in position by the skirt of the thimble which is crimped around the slug.

3. A cable connector assembly substantially as hereinbefore described with reference to the accompanying drawings.